I recently purchased a 1981 C10 with a 350 crate motor and the original transmission. I'm getting around 14mpg and figured if I had an overdrive or a better overdrive that the mileage would go up. Does anyone have any suggestions on which overdrive transmission I should look for? Also, are there gear changes in the rear end that I could make that would help? I'm not looking to squeal the tires since this is a daily driver, so I don't need something too heavy duty.
ther eis a lot of options. 700r4 is easy to swap in 4l60/4l65 are modern versions of the 700r4. 4l80 are super popular right now becaus eof there strength, easy to get, and /od. they are expensive to get and expensive to mod so you dont need the computer. the thing with regearing your axles is that you are going to lose low end and it will be noticebly slugish when taking off. you will gain top end speed and lower rpm at highway speed. it will be just as expensive as swaping an od tranny in.
Can't go wrong with a 700R4 swap. Just make sure it is set up correctly. When you are shopping around for a new or used tranny get one with a lock-up converter and a corvette servo. You can have an old one rebuilt but the servo is the weak link in this tranny. An external tranny cooler is also a must to keep it from burning up.
