Please help! I need to know which 'box I have in my '79 Z28 4 speed manual so I can get the right parts. I have the 'box in bits and the casting stamps are:

GM 40 3952847
326558 GM75
GM 3925656
19164050

VIN: 1Q87L9L533151

Looks like you have a saginaw 4sp. The case and the extension should be made of cast iron. The sidecover casting should be 3952647 check to see that the 8 is most likely a 6.

[This message has been edited by secndgn (edited 02-08-2000).]

I would have to agree. If the part number on the side cover is 3952647, then its a Saginaw trans that was used in 1977-80. The side cover will have 7 bolts, and the trans code will be "WC" which is stamped on the passengers side at the back of the main case.

If the trans was a BW ST10, it will have a 9 bolt side cover, the trans code will be "UH", and the side cover part number should be 360811.

Z28s never came with a Saginaw, so either the trans has been swapped or its not a Z.

By the way, if you have a BW trans, reverse should be located to the left and towards the engine. Saginaws were to the back.

John
79Z28

It turns out that it is indeed a Saginaw from an older car! The car is a Z28 though, everything else I've replaced/fixed up has matched, and the cowl tag matches. Thanks for the help anyway!

Sorry to hear that the trans was switched with a Saginaw. If you are doing any performance improvements to the engine you should put the Borg Warner back in. There are places that offer rebuilt Borg Warners, and Richmond Gear stil manufactures the transmission if you want one new.

Good luck,

John
79Z28