What to swap with a 350 transmission to get OD

Question

I, d like to swap out a turbo 350 3 spd, for another with overdrive. It's in a 1982 C20 Suburban. 2 wheel drive. Chevy 350 4bbl, Is there a 350 trans with OD, for this year. Or will a turbo 400 do it. ? Its because it has a trailer tow package and the gearing is 411. I,m using it on the freeway a lot for hauling wood and drywall and it could use another gear. Thanks

Augustus · Accepted Answer

You can get a Turbo 350 with a lockup converter, but it's a 3 speed unit. You can get an external OD unit ($$$). The Turbo 400 is a HD 3 speed unit only. The successor is the 4L80 series which is a 4 speed OD unit. The Turbo

350's successors are the 700R4 and the 4L60 both of which are 4 spd overdrive units. Probably a 700R4 would be the best and easiest swap but it won't be cheap.Getting proper function and shifting will take a lot of fooling around too. Why don't you simply swap out the rear end for a 3.42 unit.....way cheaper and easier to do and will save about as much gas.

ottertailfamily · Answer

Find a 700R4, it "should" bolt right in.  I put one in my 82 C10 Pickup, the crossmember had to be moved back a tad, but if I remember right most of the holes were already there.  The driveshaft fit also.  The lock up is the only thing that I never hooked up, although Summit and others sell a kit to use it.  The th350 I replaced had a lock up converter, so I could have simply wired that in. Well maybe not simply, but it could be done.   I got my 700r4 from a coworker who was converting his truck to 4 wheel drive, and it had just been rebuilt, he gave it to me for $50.  That was 10 years ago and the truck is still on the road, not a daily driver but gets about 10k miles a year.tad

none2u · Answer

What to swap with a 350 transmission to get OD

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