3spd transmission with overdrive

[Blk63vette]

Hello

I just recently went to a cruise in and was talking to a guy that had a 1965 Chevy C10 with a 327 engine with 3 spd with overdrive. Since I’m gathering parts to build my 1965 Chevy C10 and I have a 300hp 327 engine out of a 1962 Corvette it’s pretty much stock. I talked to this guy for a while and he put it in his truck and he finds it to be more driver friendly on engine. I plan on driving my truck a lot when it’s done. I heard of overdrive but never seen one in a C10 truck. I done some research and there are different types of overdrive transmissions. ( this guy had a Saginaw SM-326 3 spd with overdrive) I read on the internet 4 bolt transmission side cover and seven bolt pattern different types shift linkage etc. wiring harness and cable with overdrive T handle.

I am curious to hear from members who have them in their trucks. How rare are these transmissions? Do you guys like them? How much does a complete average 3 spd with overdrive cost? There a difference between truck and passenger car over drive transmissions? I guess I am wondering if the juice is worth the squeeze. I am interested in buying a complete unit. I want one where I can just put it in and not hunt down parts for it. I want it to be correct vintage. You can see my ad in the for sale section thanks again for your input. Be gentle I’m. Learning as I go along.
Thanks
Pete

[cwcarpenter98]

Hey Pete, I put one of those transmissions in my 63.

I got mine with everything except for the lockout cable and kickdown switch. I paid $500 for mine. It's a 4 bolt side cover.

The 4 bolt one was made from 55 to 66 or so, but I'm not sure on the exact split of the year. Borg Warner started using the 7 bolt side cover transmissions when GM started using them as well. One of my friends had that trans in a parts truck, but it was complete except for the kickdown switch. Because it was the 7 bolt side cover, it sold for $800.

I have seen more of the 4 bolt versions than the 7 bolt since I started looking for them a couple years ago. I picked up a second 4 bolt as a spare for mine a couple months back, and I saw two on craigslist sell over the weekend. The hardest part will be finding one complete and in working condition, but they are still out there. I didn't rebuild mine, and it still works great. Getting the electrical components working properly is more of a challenge than actually swapping the transmissions.

If you currently have a 3 speed with a long tail shaft, your swap will be easy. At most, you'll need to swap out the shift levers on the trans with the ones currently on your truck and possibly change the slip yoke on your driveshaft to work with the year transmission that you find. I found a 65 transmission that had different output splines than my 63 stock trans did. You won't have to shorten your driveshaft if you have the long tail shaft 3 speed. If you have a short tail shaft 3 speed, you'll have to shorten your driveshaft.

The electricals are fairly easy to set up, but making sure they work together is the challenge. I purchased the overdrive booklet by Randy Rundle. That was invaluable help in troubleshooting my electricals. There's also several threads on this site about swapping in these transmissions and getting the electricals figured out. I have mine set up as mostly stock. I only added a couple things to make it work with the HEI dizzy I am running and to make it more user friendly for what I want to do with my truck.

In terms of how rare, I don't believe they are extremely rare, but they are a popular way to add overdrive to any GM vehicle from that time period, so that's more why the price is the way that it is.

I hope that answered your question, and if you have any more, don't hesitate to ask!

Edit to add a couple pics: What I took out vs. what I installed

[Blk63vette]

Hello Christian
Thanks for the pictures and your knowledge.
Pete