[remy30006]

Hello everybody,

I'm a new member that bought a 64 GTO this summer and looking at getting a more correct differential in it. I found a doner 64 tempest at the local salvage yard. Can anyone tell me where the date codes and axles codes might be on this to make sure it is a 64 housing? Also what might the axles codes be?

Thank you for the help!

[Terry Gartner]

I don't know about dates. But, the ratio should be stamped on the right axle tube. I say that because that's what I heard. I haven't been able to find the stamp on mine. There's also supposed to be a "paint mark" on the top, but that's probably long gone. At some point Pontiac put a sticker on the left brake (two letter code) drum at some point too.

I'm new at 64's so I'm sure someone else can help more.

[The Champ]

Assuming it is an actual '64 rear end:

REAR AXLE CODES:
Pontiac used three forms of identification on the 1964 rear axles. The first is a letter stamped on the back passenger side of the axle tube. The second is a sticker containing a two-letter code. The third is a color code painted on the top of the differential and the ends of the axles.
Standard rear end: D,2D,yellow = 3.08, E,2E,white = 3.36, F,2F,blue = 3.55, K,2K,brown = 3.23, L,2L,brown = 3.23, M,2M,white = 3.36, N,2N,blue = 3.55
Safe-T-Track rear end: D,3D,green/yellow = 3.08, E,3E,green/white = 3.36, F,3F,green/blue = 3.55, H,3H,green = 3.90, K,3K,green/brown = 3.23, L,3L,green/brown = 3.23, M,3M,green/white = 3.36, N,3N,green/blue = 3.55, P,3P,green = 3.90

http://www.motortopia.com/car-clubs/...age1#post_9357

[remy30006]

Thank you for the info extremely helpful. Is there a date code or any other way to determine that its a 64 unit?


Thank you

[The Champ]

Not sure.

More info on 1965 up rear end codes and date codes:

http://www.wallaceracing.com/axledata2.htm

[John V.]

The external part of the rear axle assembly that you see under the car is the Differential Housing & Axle Tubes Assembly. The Differential Housing is the cast iron center part and the steel Axle Tubes were pressed into the Housing.

The Differential itself is INSIDE the Housing.

The same Differential Housing & Axle Tubes Assembly was used in any '64 Tempest A Body rear axle assembly, regardless of application. Only the internal ring & pinion gears would vary by application.

The cast center section Housing used in the '64 rear axle assembly will have a p/n on it.

Most of the '64 units I'm aware of have the p/n is 9773369. It is "debossed" rather than raised cast like all the others. The date code on it is a Julian date, meaning just a number like 117 which seemingly indicated the production day of either the Calendar Year or the Model Year, so either the 117th day of 1964 or else the 117th day since the start of '64 Model Year production (2 very different dates on the calendar).

The stamped codes indicate the identity of the assembly by ratio installed. It might be stamped near the vent or the brake line tab, always on the RH side tube.

It will read something like "P 256" for an open differential or "P 308 L" if the optional locking Safe-T-Track differential was used. The "P" prefix does NOT mean the rear was intended for a Pontiac, the Olds & Buick A Body apparently used the same rear end assemblies. It MAY have meant the assembly was put together at PMDs "home" Pontiac, Mich complex but nobody knows for sure.

In a thread a few years ago, dld reported on a Housing he had that showed the raised cast p/n 9773722. The date code seemed to be the more traditional style, a letter for the month, 1 or 2 digits for the day, and the last digit indicating the year it was produced. This is the only example I've heard of with this p/n but it may very well have been an alternate center section Housing casting used in the '64 rear end assemblies. Unless more are found, it remains an enigma. dld did not find a ratio code stamped on the axle tube.

Both the 9773369 and 9773722 Housings will have the small "ears" associated with the '64 rear axles, requiring the hard to find smaller on housing upper control arm bushings.

From the evidence I can recall, the Pontiac foundry began casting the new 9779822 Housing in May, 1964. This Housing was ostensibly intended for use with the '65 Model Year. It will have the raised cast p/n and the traditional style date coding tags.

This Housing was revised with larger ears to use the larger readily available on Housing bushings.

It appears that Pontiac began installing rear end assemblies with the 9779822 Housing in late '64 Tempests. I would expect to see them in June and July builds but of course late builds could also have the early style Housing as inventory was depleted. There is no known published PMD info indicating the use of the '65 Housing during '64 production, just the circumstantial physical evidence, late builds with 9779822 Housings and well matched cast dates.

The ratio coding appears to have remained unchanged into '65 production, though '65 did convert to the 2 letter manifest code style at some point (I don't pretend to know a lot about '65s).

I will be very curious to learn what Housing is found under the '64 Tempest you've spotted in a salvage yard. Hopefully it will be an original. If you can, collect the info from the Data Plate and the VIN also. Might help to tie it to the date coding on the Housing.

It is kinda difficult to describe where to look for the p/n & date code tag on the 9773369 Housing. They are on the forward RH (passenger) side. With the rear in the car, you will be looking at the Housing from the u-joint toward the rear bumper. There is a rib that divides the upper half from the lower half. The date tag is on the upper half. The p/n is debossed on the lower half. A lot easier to find with the rear out of the car, just point the yoke up in the air and look down on the front of the Housing. Hope that makes sense.

I wouldn't worry too much about the date coding. They are hard to find and beggars can't be too choosy. Besides, the stamped as assembled ratio code will likely be incorrect for your GTO. Most likely, your GTO came equipped with a 3.23 ring & pinion. The PHS doc will confirm the ratio and whether it was equipped with the locking Safe-T-Track or not. The Tempest most likely was stamped for a 2.56 or thereabouts, unlikely to have gotten a 3.23.

But if you are going for "factory correct", a '64 Housing will achieve that goal more so than a later model Housing.

Please let us know what it turns out to be.

[dld]

here are pics of that housing. that JV mentioned . i sold this to a member here.

[Dick Boneske]

Did the casting #9779822 housing have the small "ears" like the earlier '64 housings? I would think not if the 822 housing was used in '65.

[dld]

here is the 822 casting with date code k (nov.) 14 of 64 it has the large upper bushings.

[dld]

My thinking is the Pon plant cars most likely used the pontiac foundry for castings. the bop plants could have used olds or buick as well as pontiac housings. all dimensions and gear ratios were shared.

['ol Pinion head]

The '64 Pontiac usage 8.2 A-body rears, along with the '64 model BUICK 8.2 A-body rears, & the '64 Chevrolet 8.2 10 bolt A-body c-clip rears, ALL have the small cast ears on the top of the center housing.

On core rearends esp ones that exhibit quite a bit of rust, the stamped codes can be hard to find. Especially when going through dozens of core rears in big piles, many times rears are piled every which way & casting numbers & codes may have been nearly lost to the ravages of time & the elements.

On the Pontiac 8.2 rears, they are easily spotted by the twin converging ribs on each side of the center housing A pair of these wide cast ribs starts right below each upper cast perch & each side angles downward towards the nose of the housing. The lower cast ribs starts out on each side very close to the center of the housing & go forward ending up about an inch lower than the upper ribs. The bolt in axle early BUICK 8.2 10 bolt rears & the C-clip axle 8.2 Chevy 10 bolts only have a single rib on each side & are easy to spot if one knows what to look for.

Converging cast ribs on center housing & small cast (small diam bushing) upper perchs, bingo, '64 Pontiac 8.2 10 bolt.

[John V.]

Don, as I mentioned in the previous post, Buick & Olds used the Pontiac p/n Housings too.

There may have been a foundry difference between the 9773369 and the 9773722 Housings. One theory I've considered is that there may have been a metallurgy difference based on the type of iron being cast at different foundries.

There is a sorta clue about this in the Tempest Inspector's Guide. The ring gear was mounted to the Differential Carrier.

Two different Carriers were optionally used, one was malleable iron, one was cast iron. Each had a unique p/n depending on the material.

Perhaps that explains the 9773369 vs. 9773722 part nos. also.

I'm not sure where the rear end assemblies were put together. Perhaps in multiple locations and particular foundries may have supplied one location vs. the other.

I have not noticed that the Pontiac Plant used one Housing vs. the other. In my experience, the most common '64 Housing is the 9773369. And they have been found under the Tempests as well as the Olds and Buick A body.

If there was a Plant to Plant difference, you would expect the Pontiac Plant Tempests would commonly have used a different Housing, perhaps the 9773722. But since the 9773722 seems very rare, that doesn't seem to have been the case.

Need to collect more evidence.

Dick, 9779822 definitely the bigger ears. This is what makes the use of this Housing interesting in a '64 (if it truly was used as I've surmised) since the Service Parts for it would have been different. There is some verbiage in the MPC related to this, since the '64 was serviced by the '65 Housing & Axle Tubes Assembly, noted to say you need to use the '65 on Housing bushings when using this Assembly for service of a '64 (implying the original '64 bushings won't work), whereas the '64 on Housing bushings were still serviced for an original '64 Housing. But if the '65 Housing was used in late '64 production, the MPC fails to offer any clue about that.

['ol Pinion head]

Buick cast their own "single rib" gray iron 8.2 10-bolt housings & Olds used them as well. They are extremely weak, next to no pinion support, that is why Olds spec'd the early Pontiac 8.2 housings in their 4spd '66 442's. I have an original housing out of a late '64 442, I've sold the 3.36's & original axles out of it. A wholesaler friend also had the original rear, a Buick 8.2, in his late Spring built '64 442. Both cars were 4 spd post 442's.

Over the years I've pulled many many original axles out of '64-66 Buick Specials & Olds F85's. They all were the short axles with 3 "access" holes in the axle flange, notating Buick 8.2. The sealed bearing axles used in all Pontiac 8.2 rears, only has one access hole in the flange, this holds true w original bolt-in 8.2 Pontiac axles through '72.

[John V.]

OPH, I'm just realizing I missed your initial post. Read on please.

I guess I coulda mentioned the Buick cast Housing but I assume it shows a Buick Engineering p/n on it and I have no idea what the p/n is. Do you know it?

From what you say, I stand corrected if Olds and Buick did NOT use the Pontiac rear with either the 9773369 or 9773722 Housings in '64. I'd been led to believe they did use the '64 Pontiac rear for some applications by the Olds/Buick guys.

But Olds & Buick really don't interest me, except to help with donor parts.

Do you have any info about the 9773369 vs. the 9773722 housings?

I hadn't stopped to compare them before, but now that you mention the ribbing....

The 9773369 does not have the ribbing on the top of the Housing that shows for Don's 9773722. See his pic.

The '65 9779822 has ribbing similar to the 9773722, except where the 9773722 has kinda a "V" shaped rib plus an additional rib on the LH side, the 9779822 merges that single rib into the "V" so that the left side portion of the "V" is a much wider rib than the right side portion.

So the 9773722 definitely adds some reinforcement behind the yoke area (the nose).

But since I've only known of this one 9773722 while the common '64 Tempest Housing seems to be the 9773369, if the '64 GTO rear was "better" than the Buick rear, I'm not sure it was by much.

I'd really like to hear your thoughts on this.

[remy30006]

Awesome information guys Thank you! So if I understand correctly 64 unit should either be
9773369 or 9773722 with ribs that come to v by the pinion and have the small upper ears.

One question though if you don't have anything to compare can you tell if they are small ears or large?

Thank you again

[remy30006]

One more thing are the upper arms the same regardless of small or large ears?

Thank you!

['ol Pinion head]

Originally Posted by John V.

...
I guess I coulda mentioned the Buick cast Housing but I assume it shows a Buick Engineering p/n on it and I have no idea what the p/n is. Do you know it?

Do not not know it off hand, but will ck my scrap trailer, believe I still have an early Buick cast housing

Originally Posted by John V.

From what you say, I stand corrected if Olds and Buick did NOT use the Pontiac rear with either the 9773369 or 9773722 Housings in '64. I'd been led to believe they did use the '64 Pontiac rear for some applications by the Olds/Buick guys. Do you have any info about the 9773369 vs. the 9773722 housings?

Have not anally parted to the ground a ton of '64-66 Buick & Olds A-bodys like I have '68-72 A-bodys & '69-72 GP's. Have pulled a ton of axles out of all of the above. For about 7-8 years had a deal going on frames & bought off the street & out of country & crusher yards quite a few cheap early A-bodys that were often partially stripped. Then in a few days processed them on my trailer & bare frames went in a stack. Any sealed bearing bolt-in axle 8.2 rears that had axles in them, I pulled the rears & eventually pressed the bearings off the axles, also pulled what I deemed good ratio 8.2 ring and pinions, unpitted rear covers, pinion flanges. The early ('64-66) Pontiac 8.2 housings, unless they were factory posi coded rears, have never had much interest in taking notes of casting numbers or for that matter, rebuilding '64-66 8.2 Pontiac rears to sell. Have however gone through many originals for locals. My rationale on not upgrading them is one can throw a whole lot of money in a gray iron housing 8.2 & it's still only so strong. To what level, they will hold up has been fairly well determined. If these early bolt-in axle rears were a near bullet proof platform to throw 500-650 ft lbs of torque at, I'd been pulling them & hopefully still have a good supply to build off of.

Originally Posted by John V.

...I hadn't stopped to compare them before, but now that you mention the ribbing....

The 9773369 does not have the ribbing on the top of the Housing that shows for Don's 9773722. See his pic.

The '65 9779822 has ribbing similar to the 9773722, except where the 9773722 has kinda a "V" shaped rib plus an additional rib on the LH side, the 9779822 merges that single rib into the "V" so that the left side portion of the "V" is a much wider rib than the right side portion.

So the 9773722 definitely adds some reinforcement behind the yoke area (the nose).

But since I've only known of this one 9773722 while the common '64 Tempest Housing seems to be the 9773369, if the '64 GTO rear was "better" than the Buick rear, I'm not sure it was by much.

All I can come to through comparative analysis of the early GM 10 bolt rears is the Pontiac's rear axle engineers, through some understanding, figured out the small design pinion was susceptible to wanting to rise in the housing when it had so much torque thrown at it. This flexing in the nose of the housing could be minimized, to a degree, by casting the housing with these converging strengthening ribs on the sides of the center hsg in the early gray iron Pontiac 8.2 rears. Later, for '67 models as torque levels were increasing, these same Pontiac engineers decided on using nodular iron in casting their most performance oriented 8.2 STT's & HD STT's. At this same time Olds went to their "type O's" & for '68, Buick went to their HD 8.2 10 bolt.

Rears like the 8.2 Chevys & the early 8.2 Buicks, just had a single cast rib that "tied" the tube area of the housing to an area towards the "nose" of the cast center housing. In these style rears, there was a lot of flexing going on in this area once a lot of torque was able to be put to the ground. Thus early hot rodders with much stronger engines often pulled these weaker 8.2 rears, before or after they blew, & went to salvage yard 12 bolts. In parting many '65-68 Malibu's, Elco's & even Biscaynes, once a Chevy 10 bolt application was in a vehicle that was up over 270 gross hp (torque wasn't that much more) it no longer received a weak 8.2 Chevy 10 bolt. In the chevy world, even though this era's 327 4 bbl small blocks were far from big time torque engines, once that stock 270 hp point was passed, in went a std duty 12 bolt.

Other style GM A-bodys rears, like the Pontiac 8.2's, the Chevy 12 bolts, the type "O" Olds, the '68-70 BUICK 8.2's, & the later 8.5's all have some design of twin strengthening ribs to reinforce this area of the center housing. First noticed several of the differences in the center housing designs nearly 30 years ago when installing & removing lakewood hop stop bars. With the hop stop bars, you're supposed to drill holes & pin the hop stop bars to the cast reinforcement. These decades old hop stop bars raise the pick up point of the upper controls arms. Due to different A-body housing designs one pair will fit one style of early GM A-body rear, but wont always fit another GM design. As I started building all forms of these rears, the center housing designs became even more fresh & easy to spot.

[dld]

Look closely at pic i posted of 64 housing. check out meat around hole . the large 65 rear is much bigger. also could go to local parts house and measure 65 bushings . they will not have the 64 bushings. PY and Ames do . for years the 64 bushing were hard to find.

the upper arms are same AFAIK if BOP. Chevelle are different i think. however i have seen (pont) stamped on some of the uppers

[John V.]

OPH, good stuff. I'll need to look thru all that.

remy30006, the 9773369 will NOT have the V ribs.

I'm also curious about the '64 vs. '65 upper control arms.

There WAS a p/n change and the '64 was serviced separately from the '65, so I would guess there is some sort of difference but maybe they interchange?

OPH, do you know.

I have a set of arms marked PONT but they were used with a 9779822 '65 rear.

So I am also curious if the upper arms interchange for a '64 & '65 rear.

[John V.]

Okay, I'd still like somebody to confirm, but it looks like the LENGTH of the '64 on Housing bushing is the same length as the '65 on Housing bushing, so the '65 arms should work on a '64 Housing and vice-versa (bushings are same on the other end).

Only the dia. of the on Housing bushing seems to have changed from '64 to '65 but that doesn't affect the arm.

Not sure yet why the '65 control arm p/n is different from '64 though, so still wondering.