[Terry M. Hunt]

I am trying to put together a numbers matching trans(as close as I can get with what I have available) for my '65 GTO built during the first week of January 1965. I have lots of info that has been published on code numbers, etc., and, as you might expect, not all of it is consistent. I have scrounged around through my spare parts and come up with the following:

Case- 3885010 It has a production date of P0105 ,which I'm reading as January 5th. It has 19551 stamped across the top of the front edge of the case, which I'm reading as the last digits of the VIN of the car where it was originally installed. The case does not have a drain plug.

Bearing retainer-3851326

Side Cover-3884685 There is small metal tag attached via one of the side cover bolts stamped with 9784425. Not sure what this number indicates.

Tail extension-GM 3846429 Speedo fitting is on Driver Side. There is a number "2" handpainted in black behind the shifter mounting plate. I have a second extension 3857584GM, but speedo fitting is on Passenger side, so I'm thinking this is '66 and later.

I realize any VIN stamped into the case is never going to match my car's VIN. I'm just trying to get as "correct" as I can using stuff I already have to avoid having to track stuff down.

I'm thinking of sending these pieces to Auto Gear to have them install all new internals.

[72pontiac]

i thought my 65 built the 3rd wk of jan 65 was close to my birthday jan 8 but yours really is close to my b day

[Jerry H.]

Terry, I've forgotten 99% of what I've learned over the years. What is telling you this is a Pontiac tranny, is it the 'P'0105? Or the part #? Just wondering because I do remember the early Chevy Muncie's having the speedo fitting on the passenger side.

The tranny that I had in my old red 65 was a Chevy tranny with the speedo cable on the passenger side.

[Billy's Goat]

Terry, I went through this about a year ago on my 65. I have a Fremont, mid-December, 1964 built car. I found that the correct numbers for a M-20 (which mine originally had) are:
Main Case: 3851325 (with no vin - 65's didn't have vins on trans) - no drain plug
Tail Shaft Hsg.: 3841629 (speedo connection on drivers side)
Shift Cover: 3831707
Input Bearing Hsg.: 38561326

[Old Goat Racer]

Well, my original 4-speed has the vin# stamped on it and a drain plug, P0607 June 7th
Main case 3851325, tail housing 3846429, speedo on drivers.

[Old Goat Racer]

And the P stands for Muncie

[Terry M. Hunt]

I'm using articles from Hemmings Muscle Machines(Jim O'Clair), Muscle Car Review 9-99(Alan Colvin), Muscle Car Review 9-95(Dave Emanuel) with an accompanying code chart by Greg Donohue, and www.5speed.com.

Case codes:
O'Clair shows case code of 3851325 for '64-'65 and 3885010 for '65-'67.

Colvin's code chart uses all Chevy examples, and he does not show case 3885010 appearing until '66.

Emanuel's article includes a photo of case 3885010 with prod code of P6C28, which he decodes as P=Muncie 4 speed, 6=1966, C=March, 28=28th day of March. This is consistent with what both O'Clair and Colvin write.

www.5speed.com has a chart showing case 3851325 as 1964-'65 7/8" Bore Patent Number and case 3885010 as 1966-'67 1" Bore Patent Number. Unfortunately, they have a second chart showing case 3885010 as 1965-'67(like O'Clair), so this web site is inconsistent on the case numbers.

Tail extension:
O'Clair gives only one example as 3857584 indicating this is for 1965-'70 passenger car with 27 spline output shaft.

Colvin's Chevy only application chart shows 3846429(Early) with a footnote saying this extension was made in two versions, a "thin rib" and a "wide rib" and that the '64 full size Chevy used the thin rib. His application chart goes on to show 3846429(Late) with a footnote saying the '64 Chevy II used the wide rib, which was apparently carried forward until 2-65, when tail extension 3846429 was replaced by 3857584.

Emanuel's article does not provide numbers for tail extensions.

www.5speed.com shows 3846429 as "1963 Thin Fin Tail /Driver Speedo/ 27 spline" and also shows 3846429 as "1963-1965 Regular Thick Web/ Driver Speedo/ 27 spline". This seems to agree with Colvins info showing an Early and Late version of this part.

Side Cover:
O'Clair describes the side cover but provides no numbers.

Colvin's chart shows 3831707 for 1963-'65, then 3884685 for 1966-'68.

Emanuel's article provides no numbers for side covers.


www.5speed.com shows 3831707 as 1963-'65 Early side cover/stud type shift shafts and
3884685 as "cover issued with 584 tail/stud type shift shaft."

Jerry, the prod code P0105 supposedly decodes at P=Muncie 4 speed, 01=January, and 05=5th day. M was evidently the code for 3 speed Muncie. I haven't found any info yet that seems to identify which of these transmissions or their parts were intended for Pontiac, Chevy, etc. I'm not sure if there were unique numbers used for different GM divisions.

This is getting interesting. Anybody else have any input?

[dld]

May want to review this thread. It scans over this subject

http://forums.maxperformanceinc.com/...ghlight=colvin

[Terry M. Hunt]

Thanks for this link. I'm printing this discussion to study through later on this evening.

[bigpop]

65 VINs are stamped on the top,last 5-6 digits. Book it! Larry B.

[John V.]

Terry, the p/n tag 9784425 attached to the side cover indicates a '66 2.52 1st gear Muncie destined for a '66 Pontiac Tempest/GTO.

The partial VIN was definitely stamped on the main case of the Muncie 4 spds at least as early as '64. The typical stamp location changed from '64 to '65 and may have changed again in '66. Billy's Goat, could be they missed one, but that was the exception not the rule. In '64, Fremont stamped the partial VIN on the left side top of the rear flange of the main case as F001234. '65 VIN format was revised, Fremont Plant code became "Z". Presumably the 4 spds were VIN stamped because 4 spd thefts were already rampant in the early '60s, the VIN stamp was an attempt at theft deterrence.

The '66 Muncie underwent significant changes from '65. Chevy may have introduced the revised design as a running change for the '65 Model Year, AFAIK, Pontiac did not introduce the revised Muncie until the '66 MY.

In '64 & '65, two different versions of the wide ratio were used in the Tempests & GTOs, each with a specific p/n, manifest code W for 99% of the applications, code 9 in combination with 3.90 rear axle (the code 9 trans was distinct from the very late '64 p/n 9777000 and '65 p/n 9780986 code 8 2.20 1st gear close ratio M21 only available as a special equipment option with Tripower GTO/3.90 axle). Only difference between the two wide ratio Muncies was the internal speedo drive gear, 8 tooth for the code W, 6 tooth for the code 9.

Both had the 2.56 1st gear.

For the revised '66 wide ratio, only one version was used. It had a 2.52 1st gear. Various changes eliminated the need for the specific code 9 trans for wide ratio/3.90 axle applications in '66 (the code 8 close ratio could still be special ordered for a Tripower GTO/3.90 avle).

The '66 main case was revised to suit the larger dia. countershaft and there were some revisions internally to the synchro rings and sleeves to beef them up. You can use these pieces in an early case as matched sets. Of course, you can't use the larger dia. countershaft in an early case.

For a '65, you would want the later "wide rib" 3846429 extension. And the 3851325 main case with the squared off (rather than bullet shaped) top rear bolt lug (I think I discussed that in the earlier referenced thread).

The P0105 is the date of trans assembly. Unfortunately, since Muncie did not add a Model Year designator to the date coding until '67, you need to rely on other clues to determine the Model Year associated with a given trans.

I believe the date stamp location also changed at some point, for '64 it is located on the machined face at the lower left corner of the side cover opening on the main case.

Hope this helps.

[John V.]

Correction, the '64 date code is on the machined face at the lower RIGHT corner of the side cover opening on the main case.

Had a brain cramp.

[Billy's Goat]

Originally Posted by John V.

Terry, the p/n tag 9784425 attached to the side cover indicates a '66 2.52 1st gear Muncie destined for a '66 Pontiac Tempest/GTO.

The partial VIN was definitely stamped on the main case of the Muncie 4 spds at least as early as '64. The typical stamp location changed from '64 to '65 and may have changed again in '66. Billy's Goat, could be they missed one, but that was the exception not the rule. In '64, Fremont stamped the partial VIN on the left side top of the rear flange of the main case as F001234. '65 VIN format was revised, Fremont Plant code became "Z". Presumably the 4 spds were VIN stamped because 4 spd thefts were already rampant in the early '60s, the VIN stamp was an attempt at theft deterrence.

The '66 Muncie underwent significant changes from '65. Chevy may have introduced the revised design as a running change for the '65 Model Year, AFAIK, Pontiac did not introduce the revised Muncie until the '66 MY.

In '64 & '65, two different versions of the wide ratio were used in the Tempests & GTOs, each with a specific p/n, manifest code W for 99% of the applications, code 9 in combination with 3.90 rear axle (the code 9 trans was distinct from the very late '64 p/n 9777000 and '65 p/n 9780986 code 8 2.20 1st gear close ratio M21 only available as a special equipment option with Tripower GTO/3.90 axle). Only difference between the two wide ratio Muncies was the internal speedo drive gear, 8 tooth for the code W, 6 tooth for the code 9.

Both had the 2.56 1st gear.

For the revised '66 wide ratio, only one version was used. It had a 2.52 1st gear. Various changes eliminated the need for the specific code 9 trans for wide ratio/3.90 axle applications in '66 (the code 8 close ratio could still be special ordered for a Tripower GTO/3.90 avle).

The '66 main case was revised to suit the larger dia. countershaft and there were some revisions internally to the synchro rings and sleeves to beef them up. You can use these pieces in an early case as matched sets. Of course, you can't use the larger dia. countershaft in an early case.

For a '65, you would want the later "wide rib" 3846429 extension. And the 3851325 main case with the squared off (rather than bullet shaped) top rear bolt lug (I think I discussed that in the earlier referenced thread).

The P0105 is the date of trans assembly. Unfortunately, since Muncie did not add a Model Year designator to the date coding until '67, you need to rely on other clues to determine the Model Year associated with a given trans.

I believe the date stamp location also changed at some point, for '64 it is located on the machined face at the lower left corner of the side cover opening on the main case.

Hope this helps.

Great info John V. This confirms some of what I've been able to get plus adds some new/clarification. I really enjoy finding out these details and exceptions/applications.

[Terry M. Hunt]

More very good info. I'm still debating which way to go, but sending my case, etc. to Auto Gear for a new set of internals seems to be the best idea right now. I'm sure their totally new trans is an amazing piece, but $2000 is a pretty amazing price also.

[bill ryder]

I left myself a note to post these when I got the drive train pulled for detailing. Probably to late now. The VIN is stamped on the main case to the side of the upper rh mount bolt. The date code P 1216 on the bottom rh flat for the side cover. No good pics of the date code!!!

[Pontirag]

also if the speedo gear exits off the passenger side isn't it a tailshaft housing from a camaro or firebird?

[John V.]

Bill, interesting pic. Apparently the Pontiac Plant stamped the complete VIN on the top of the main case front flange in '64 and even stamped the Manifest Code (W, in your example).

Fremont and KC, I think Balt also, omitted the '64 VIN prefix (824 in your example) and did not stamp the manifest code as far as I know.

Pontirag, originally the Chevy 4 spd speedo gear was on the LH side, same as used by Pontiac, same extension housing p/n. At some point in time, they switched to the RH side and their extension housing carried a different p/n vs. the Pontiac trans extension housing at that point.

To my knowledge, Firebirds would have gotten a Pontiac 4 spd, speedo gear on the LH side. Camaros would have been same as all other Chevy 4 spds, speedo gear on the RH side. I think this was true all the way back to the Camaro intro for '67 as I think Chevy had made the switch by then. A Chevy or Muncie expert should know for sure.

The VIN stamp, regardless if it is a partial or full VIN stamp, will also identify the original application of the trans. Pontiac VIN formats were different from Chevy VIN formats (or Olds or Buick for that matter).