Transmission swap

[80midnightchevy]

Hello all. I recently bought a 1980 c-10 and have a few questions as it is my first rebuild project. The vin has it as having the inline 6 engine, but getting the serial number off of it and calling gm and doing further research, it's a 305 from a 78-79 camaro. Currently the transmission slips out of gear and goes into neutral. So I know that I need to get a new transmission, and do not want to necessarily want to rebuild it because I'm not sure how old this transmission is, and have never done a rebuild on one before. Since this is not the original engine, does the TH350 tranny that's in it come stock for the engine, or the truck? Also, do the transmission mounts go to a certain engine to a certain tranny or is it generally a one size fits all deal? I am currently in okinawa japan and will be back stateside in march/April and am planning on doing a cross country trip, roadkill style. Any info would be greatly appreciated.

[LTZ C20]

Well first off, welcome to the site from california.  You said your in japan, Okinawa is a military instalation correct, naval base? If your there with the military, may I say THANK YOU VERY MUCH for your service.

As to your truck, alot of these engines and transmissions will fit multiple vehicles. TH350s did come in camaros and the trucks. That is dependent on which engine it had tho, typically a 350 engine or smaller would normally have a TH350 and 400 engine or bigger would have a TH400. I'm no expert on camaros either haha. I'm better with the trucks for sure lol. As far as I know, the mounts for the transmission fit with the truck because of the mounting style, the crossmember, the camaro could be different or not.  not sure.

If your looking to get a new transmission that would be correct for the truck, I would suggest a 4 speed auto like the 700R4, has an extra gear for highway miles and a lock up torque converter. I would also suggest if you do get one is the later year models, such as an 89. A well built 700 will last a long time. Mine is built to withstand about 500 horsepower, but I'm only throwing about 360 to it.

[80midnightchevy]

Okinawa is an island within the Ryuku chain of islands as a part of Japan, and I'm a Marine. Thank you for your support.

As for the transmission I have done some reading on the differences in the 350/400/power glide transmissions, nothing really on the 700r4. The main reason behind my post was, if I change out the transmission, will I need to do any type of fabricating. I do not have a blow torch, grinder or welder, I'm sure I can find people that have them, but I'm trying to keep it as simple as possible.

[zieg85]

Thank you for your service.  GM made TH350's with 3 different length tail houses.  Anything is possible and the only real change is where you have to bolt the cross member based on what trans is in it.  There was also a 1 piece drive shaft or 2 piece.  If the truck was ever a 3 speed manual a short tailshaft TH350 could be in it.  TH400 takes a larger slip yoke and some TH400 has a bolt on yoke that you bolt a u-joint right to it, kickdown function it an electric switch on the gas pedal.  Hard to say on a 35 year old truck without looking.  I've pieced stuff over the years myself and have seen it done having roughly 100 with all the ones I've parted out.  If you have a mid length TH350 the 700R4 is a direct drop in but the cross member is moved.  The kick down cable now becomes the TV cable which takes special adjustments to get it right.

[LTZ C20]

Cool deal! Happy to support! As zieg said, alot of things are bolt in or close to it. All I had to do for the 700 to fit where my 350 was, was move the crossmember back about 2 inches or so. Adjusting a tv cable properly is not hard as long as you know the proper steps and sequence, and that's not hard either. I've readjusted and changed and readjusted mine probably 20 times to get what I want. For a stock engine, you can set it and forget it.

Moving the crossmember only required normal hand tools, wrench, sockets and a drill bit to drill new holes in the frame for the crosmember, was a 1/2 hole I think, don't remember for sure tho. It's really up to you as to what you want, a 400 is a great trans too, just about bullet proof really. My 700 has no problem at all moving the ponies to the rear either lol.