[68Catalina68]

Hey guys, been gone for a bit working on my 69 Chevelle...I know, ha. I thought the rear was replaced with a 10 bolt chevy posi but when I started to look into it I found its a BOP.

Casting number on the housing is 9793235, from what I found on the interwebs. Is this correct?

Ratio: 4.33

Posi: ZL

Model: GTO

4 PINION 9793235

[68pongto]

Yes that is correct, you could sell it and buy TWO Chevy 12 bolts!

[68Catalina68]

Originally Posted by 68pongto

Yes that is correct, you could sell it and buy TWO Chevy 12 bolts!

I find that very hard to believe lol. Did that rear only come in one gear ratio? Is there another number I should be looking for?

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[68pongto]

Originally Posted by 68Catalina68

I find that very hard to believe lol. Did that rear only come in one gear ratio? Is there another number I should be looking for?

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No other numbers to look for, you have all the important numbers listed. You could check the actual ring and pinion and see if it still has the 4.33 gears in it. That is a nudular rear end, there should be a large N cast on top of the center section above the pinion. The 4.33 gears were mandatory in all 68 Ram Air GTO's. They were optional on other cars, with restrictions like no A/C, etc. The nodular rear ends would have been available with 3.55 to 4.33 gears, but I did find a Nodular rearend in a 68 LeMans parts car that had 2.56 open, but that is an anomaly. Either way they are highly sought after rearends, especially withe ZL code and 4.33 gears.

[PurelyGTO68]

As mentioned already.....a fairly valuable axle there. Especially if the HD 4 pinion carrier, gears and HD axle shafts are present.

There should be a 3 digit date code cast in the center section and another 3 digit date code stamped on the LH tube near the ZL stamp. I think the date code on the tube might be the assembly date of the complete axle assembly so it should be a greater than the number cast in the housing. The date code might be important to a future owner.

Nice find.

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[Tellyshavilli]

Originally Posted by 68Catalina68

I find that very hard to believe lol. Did that rear only come in one gear ratio? Is there another number I should be looking for?

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68 rear , good find. What kind of shape is it in. ?

[68pongto]

As for the date code, Nodular rears used the julian date codes. So it will just be 3 numbers for the day of the year. Standard axles used the normal GM date codes like B158, that would = Feb 15 1968.

['ol Pinion head]

Originally Posted by 68Catalina68

Hey guys, been gone for a bit working on my 69 Chevelle...I know, ha. I thought the rear was replaced with a 10 bolt chevy posi but when I started to look into it I found its a BOP.

Casting number on the housing is 9793235, from what I found on the interwebs. Is this correct?

Ratio: 4.33

Posi: ZL

Model: GTO

4 PINION 9793235

Nothing BOP about that rear. Olds did not use it, Buick did not use it!

Correct identification is:

'68 HD version of the early Pontiac 8.2 10 bolt, complete with the '68 nodular iron Pontiac 8.2 A-body center housing, 4 pinion Safe-T-track carrier, and should have a pair of original HD forged axles.

[68Catalina68]

I jacked up the drivers side wheel and two full turns gives me a 3.5 turn of the drive shaft. I assume this means I have a 3.55 ratio rearend.

[Tellyshavilli]

Originally Posted by 68Catalina68

I jacked up the drivers side wheel and two full turns gives me a 3.5 turn of the drive shaft. I assume this means I have a 3.55 ratio rearend.

Make sure both tires are off the ground and do one turn

[Baron Von Zeppelin]

Originally Posted by 68Catalina68

I jacked up the drivers side wheel and two full turns gives me a 3.5 turn of the drive shaft. I assume this means I have a 3.55 ratio rearend.

That would mean its a 3.55 Non-Posi , Peg Leg

Might be everything inside has been swapped out.

Or the just the ring and pinion swapped , and the posi cones completely worn out.
shet happens

['ol Pinion head]

Have ran across quite a few original coded '68-70 Pontiac 8.2 3.90 & 4.33 HD Safe-T-Track rears that gave up their digger ratio R & P at some time for a set of 3.55's or early dated 3.36's. Not that uncommon, and both ratio's are avail aftermarket or in select used for the '64-69 style Pontiac 8.2. The '70-72 Pontiac 8.2 version with 1/16" larger diam LH thread ring gear bolts are not reproduced, but that issue can be solved several ways.

['ol Pinion head]

Never trust stamped ratio codes on a housing or spinning a drum and counting. Too many times gears have neen changed, then we there is the crowd with the cheap (and incorrect font) stamps & a big hammer. Its just too easy to drop the rear cover, drain the r/e grease, and examine the ring and pinion and carrier. Might be surprised what you find!

Most different GM ring and pinion designs used a ring gear with factory incribed part number, ratio code like 39 11 (3.55) and date code mfg. I've pulled many many original early 12 bolt gearsets where the original ring gear was stamped one month of a year and the ring gear was stamped 1 or 2 month earlier or later. This type deal also happened with other factory ring and pinions like the early Pontiac 8.2 10 bolt. Typically, nothing to be concerned about.

[68Catalina68]

Originally Posted by Baron Von Zeppelin

That would mean its a 3.55 Non-Posi , Peg Leg

Might be everything inside has been swapped out.

Or the just the ring and pinion swapped , and the posi cones completely worn out.
shet happens

She is definitely a POSI, ha

69 Chevelle SS by chevellecarcass, on Flickr

[68Catalina68]

Originally Posted by Tellyshavilli

Make sure both tires are off the ground and do one turn

Just verified, ring gear is stamped 39 11.

3.55 Limited Slip Rear

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[68Catalina68]

Originally Posted by 68Catalina68

Just verified, ring gear is stamped 39 11.

3.55 Limited Slip Rear

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Pics

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