The Stovebolt Site Forums The Shop Area Driveline What tranny do I have here?

I have an SM318 3-speed tranny in my 1950 half ton that went bad. Found an ad for a 235 motor with a 3-speed attached, so I bought the tranny, removed it and brought it home. Its tight, doesn’t leak, with no rattles at all. Upon closer inspection the U-joint looks different than what’s on my SM318. Can someone please look at the pics and tell me what tranny it is and if it can replace the 318? Maybe I will need to replace the U-joint? Help is much appreciated.

Chuck, I did a quick check of the main case and tailshaft housing casting numbers and they came back as correct for 1948-54 Commercial 3 speed transmissions. Your pictured output shaft rear yoke looks to be for a 3/4 ton (3600) truck - looks same as this 3/4 ton yoke/u-joint kit which is different than the ones used by both Chevy trucks and cars of the same years.

Check the Shop Manual for how to disassemble/remove the yoke/u-joint currently there. Then you should be able (I think) to transfer your original yoke/u-joint set to this transmission. Other Bolters with more experience will surely come along to provide more info.

Dan, I think you’re spot on that this tranny was in a 3/4 ton truck. I knew the U-joint looked beefier than mine. The pic in Flea-bay is definitely the one on this tranny. Thanks for your detective work!