Best auto tranny for gas mileage?

[kyleholt11]

I have been plagued with tranny problems and gas milage problems with my 1983 chevy silverado...What would be the best auto tranny that would fit on a 305? Im currently getting 8 MPG....

[wafrederick]

The 700R4 is the best for gas mileage.The reason is beacuse it already has the overdrive in it.The turbo 350 and 400 do not which are 3 speed transmissions and you have add an overdrive unit from gear vendors which is more money.

[kyleholt11]

What vehicles have a 700R4 in them? My plans are to go to a salvage yard (u pull it auto parts) and pull a tranny out of another truck...

[wafrederick]

About 1984 and up cars and trucks.Go with a 1988 to 1991,1992 transmission.

[Ratt643]

If you don't plan on hauling heavy loads or hauling frequently, the 200-4R could be another option. Both the 700r 4 and the 200-4r will work but the 200-4r is the same lenght as a 350 turbo, so no cutting the drive shaft! The crossmember may have to be relocated.You can buy a kit from Painless wiring(out of Summit,Jegs or whoever) to wire in the convertor to lock-up at highway speeds. You will also need a geometry corrector bracket to go on to carb linkage to properly adjust the throttle valve cable. YOU MUST hook up the throttle valve cable(looks like kick down cable on 350 turbo) and adjust it properly or you will have a crispy fried tranny. Alot of people give the 200-4r a bad rap, but they are good trannys as long as you don't abuse them. If you decide to use a big camshaft and ned astall convertor, just get one for an Odlsmobile Cutlass diesel,(mid to late 80's) they are rated @2600 rpm stall. You might want to install a shift kit to firm up the shifts as they typically slide into gear(old people like that instead of one shifting firmly). Make sure that if you tow with an overdrive,put it in 3 or the torque convertor and fourth gear clutch pack will fry. Good luck

[MrPbody]

Actually, we've experienced better service from TH200-4R in high-torque applications (big blocks, Pontiacs) than TH700-R4. Put a billet sun shell and sun gear in there, and it will live fine behind the little Chevy. 700 is fine for the 305 as well, I just wanted to point out the qualities of the 200-4R.

Jim