The Stovebolt Site Forums The Shop Area Driveline 1965 3 Speed Transmission

I have a 1965 Chevy C20 with a 3 speed tranny and a 292 engine. I am looking at a 3 speed tranny on Craig's List that came out of a '65 GMC 1/2 ton with a 6 cylinder. The numbers on the transmission do not match those on my transmission. Would they have to match in order to swap out the transmissions? Thank you.

As long as the bellhousing bolt pattern and the input and output splines match up, and the overall length is the same, they should swap. I think there might have been more than one ratio selection on the 1st. and 2nd gears. 3rd. will always be direct drive, a 1:1 ratio. Do the cases look the same? By 65, I think all the 3 speeds were the fully-synchronized Saginaw units.
Jerry

Thank you for your reply Jerry. I'm no mechanic but I will try to figure this out based on your information. I don't need the transmission but I might grab it if I can for a spare since it is probably hard to find these. Rob

Measure the length of the transmission and count the number of bolts on the side cover. I owned an un-modified 66 C-20 that I purchased from the original owner. It came with a 292 I-6 and the short housing Muncie 3 speed. That transmission is approximately 15" long has a non syncro first gear and has a 4 bolt side cover. It is likely the GMC used the same transmission. However, if the other transmission has a 7 bolt side cover and is about 22" long it is likely a Saganaw. You would have to modify your driveshaft to use it.
Fred

Thank you Fred. That helps alot. I will check out my transmission and count the bolts but I do believe the one on Craig's List is a Saganaw. I also do know that my tranny has a non-syncro first gear (having learned the hard way!).

Most sellers don't know if they have a Muncie or a Saganaw, they mostly rely on fuzzy information that they have been told by someone that doesn't know for sure. The terms get mixed up a lot.
Fred

I believe you - I'm confused too!

GM made a wide variety of transmissions in that era. What you have is a garden variety SM318 short tail-shaft Muncie. Earlier models had a long tail-shaft. There is also an overdrive offered along with some internal gear ratio differences. It doesn't really matter what they call it, if it has the same physical dimensions as yours it should work.
Fred

There was a heavy duty option 3 speed back then. It was a Borg-Warner. The syncro 1st gear did not come out till 67. You need to watch the shift linkage also when juggling trans. There are variations in that.

Thank you both. I think you are correct about what I have Fred. I measured it today and it is about 15". The one I was looking at won't work because it is a long shaft. Thanks to all for your help in figuring this out. Rob