1975 3/4 ton drivetrain options

[seavalos]

Father has a 75 Chevy 3/4 ton dual gas tank long bed Bonanza Camper Special that the automatic transmission is shot. Would like to know what tranny could I place in there without doing any mods?  Would like to just swap in something that is newer without having to shorten or modify anything. Ask me about a mustang and their drivetrain and I’ve got you covered. But this, this is new to me.


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[Henry]

Hi Seavalos:
It would seem to me that if you dont want any mods you just have a reputable trans shop rebuild what you have in there now. If it is the original trans, it most likely is a TH400 for a camper special...this is a good heavy duty trans that is readily rebuildable. A TH350 is also readily available and reliable but is not as strong for towing and load carrying and will need the driveshaft changed. If you do decide to change the trans away from a TH400, be aware that the TH400 is somewhat collectible by the hot rod and dragster guys so dont just give it away.
Regards,
Henry

[seavalos]

Thanks. Nice to know the 400 is a collector tranny!  Will do more research on the truck!


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[75gmck25]

Based on research I've done, its probably a TH350, since that was used on most 3/4 ton trucks in 1975 (even the camper special).  There are a lot of rebuilt performance TH-350s available, and that is probably the easiest choice.   Its a very reliable transmission, and with some minor upgrades it holds up very well in a truck.

If you don't want to change the driveshaft, I think the 200R4 overdrive trans is almost the same length as the TH350.  However, many 200R4's were used in light duty vehicles, so you need to get one that is built to handle the power of your truck.  The 700R4 overdrive trans is also an easy swap, but you will need to have the driveshaft shortened, or get a driveshaft from a later square body truck.

Bruce

[Irish_Alley]

two things you can do IMO. one is replace with a like trans or get a donor with the same setup (i.e. same bed and either 4x2 or 4x4) that way you can use those driveshafts. if you look for a donor you might be able to find a 700r4 which then will save you a little in gas

[seavalos]

Thanks all! Helpful to know which trannies to be looking at. More research to do. Appreciate everyone giving me help.


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