Differential codes - 1962

[SRReality]

I can find these codes stamped/cast on my differential (1962)

Passenger side, BB 205
Driver Side, B 1 62
3725899

I have decoded all the other components on this baby, but not the rear end.

Can one of you reference book owners out there help me out? Thanks!

 

[Vettefreak100]

The 3725899 is a non-positraction differential. B-1-62 means that it was cast on February 1, 1962. The 205 stamped on the passanger side means that it was assembled on February 5, 1962. The BB is where my chart stops giving me information. These letters determine what type of gear ratio the car came with and whether it has a posi-unit (as well as a giant P on the drivers side of the casing). All 1962's had a C as the first letter to identify the rear axle ratio. My 61' had BB like this stamped in the case....I think...and it was a 3.36 ratio. In another post, someone said that BB means it was out of a passanger car, but I do not think that it would have the same part number as a Corvette. Check to make sure that BB is in fact stamped in the casing.

This is the other forum where the diff numbers were discussed
http://www.corvetteactioncenter.com/forums/showthread.php?t=79502

Doug

 

[SRReality]

The 3725899 is a non-positraction differential. B-1-62 means that it was cast on February 1, 1962. The 205 stamped on the passanger side means that it was assembled on February 5, 1962. The BB is where my chart stops giving me information. These letters determine what type of gear ratio the car came with and whether it has a posi-unit (as well as a giant P on the drivers side of the casing). All 1962's had a C as the first letter to identify the rear axle ratio. My 61' had BB like this stamped in the case....I think...and it was a 3.36 ratio. In another post, someone said that BB means it was out of a passanger car, but I do not think that it would have the same part number as a Corvette. Check to make sure that BB is in fact stamped in the casing.

This is the other forum where the diff numbers were discussed
http://www.corvetteactioncenter.com/forums/showthread.php?t=79502

Doug

Thanks for the info! I'll check the "BB" stamp again. I don't think it's 3.36 now, because I turn about 3200 RPM at "highway" speeds. I'll do the "wheel turning thing" and see what I get for axle ratio. Thanks again!

 

[JohnZ]

It's a pumpkin out of a '62 passenger car; the two-digit year code in the casting date says it was cast at Tonawanda and machined/assembled at Buffalo; all Corvette pumpkins were cast at Saginaw (one-digit year code) and machined/assembled at Detroit Gear & Axle, although pumpkins from either location were physically interchangeable between Corvettes and passenger cars.

 

[Vettefreak100]

Interesting. Where did you find your inforamtion? I was curious because I can always find information about the axle codes on Corvettes, but had trouble finding anything on passanger cars.

 

[SRReality]

It's a pumpkin out of a '62 passenger car; the two-digit year code in the casting date says it was cast at Tonawanda and machined/assembled at Buffalo; all Corvette pumpkins were cast at Saginaw (one-digit year code) and machined/assembled at Detroit Gear & Axle, although pumpkins from either location were physically interchangeable between Corvettes and passenger cars.

Thanks for the additional info. I'm sad to hear it isn't a "Corvette" center piece, but it works fine.

While I have your "ear", John Z, on a scale of 1 to 10, how hard is it to replace an open rear-end with a positraction set-up? I have an idea of the expense involved.

 

[Vettefreak100]

Thanks for the additional info. I'm sad to hear it isn't a "Corvette" center piece, but it works fine.

While I have your "ear", John Z, on a scale of 1 to 10, how hard is it to replace an open rear-end with a positraction set-up? I have an idea of the expense involved.

The difference between the non-posi and the posi centerpiece is a rib that is cast into the open differentials that has to be ground out of it to install a posi unit. Other than that it's just installing it....provided that you can get a positraciton unit. US Gear makes a unit, but it can sometimes take months to get one.

 

[SRReality]

The difference between the non-posi and the posi centerpiece is a rib that is cast into the open differentials that has to be ground out of it to install a posi unit. Other than that it's just installing it....provided that you can get a positraciton unit. US Gear makes a unit, but it can sometimes take months to get one.

I've seen them in the NCRS monthly "newsletter" and on Ebay ocassionally - - - $1100 plus as I recall. I'll leave it my "back burner" list of things to do "someday"...........Thanks for the information. I didn't think it would be a "plug and play" exchange!

 

[JohnZ]

There were two different pumpkin castings - one for Posi (3743833 for '57-mid-'61, and 3789812 for mid-'61 through '62), and one for open - the Posi casting is the same as the open casting except it doesn't have the cast-in rib inside. Eaton now makes nice, fresh Posi units for C1 pumpkins for about $400. Pumpkin swap takes a couple of hours.

 

[SRReality]

There were two different pumpkin castings - one for Posi (3743833 for '57-mid-'61, and 3789812 for mid-'61 through '62), and one for open - the Posi casting is the same as the open casting except it doesn't have the cast-in rib inside. Eaton now makes nice, fresh Posi units for C1 pumpkins for about $400. Pumpkin swap takes a couple of hours.

Thanks, JohnZ - - - so it's either cut/grind out the rib or get a Posi axle housing, plus the center piece, of course?

I wonder what the chances are of locating an axle housing from the right "date line" ahead of my Vet's birth date? That oughta keep me researching for awhile.

Thanks again.......