GM casting numbers

[78repowerwagon]

I need some help identifying a GM manual transmission. It came out of a ?69? c-10 pickup with a 283. I have no idea if it is the original or not. It is a top loader with casting number 3901127 on the trans case.



Thanks,

Matt

 

[JFitzgerald]

Can't help with the number, but by your description, the trans should be an SM465, which replaced the SM420 in about '68. These are the most common GM top loader 4 speeds. The easiest way to tell the difference between a 420 and a 465 is that the 420 has reverse to the left and back, where the 465 has reverse to the right and back. Hope this helps.

 

[78repowerwagon]

I will check that out. I have to pull the top off, is there anything inside that I can look for?

 

[JFitzgerald]

Here are a couple good links with more details.



SM465



SM420