changing TH350C Lock-up to 700r4 OD a few questions

[d stroud]

Hey fellows,

I've got an '85 GMC Sierra Classic pick-up that has been my faithful daily driver for the past 3 years and I've decided to give her a little make-over this fall.

Right now it still has the factory 305 weezer and TH350 lock-up tranny.

I restore and show ole GM Muscle cars and use the Truck often to pull cars, usually in very mountianous areas and they really work on the little 305 to get the car and trailer over the mountians.

I've got a fresh and not so mild Vortec headed 383 and a built 700r4 tranny that I'm planning to swap in along with a drop and new paint.


My question is, will the currenty lock-up feature for the TH350C work on the 700r4?  Other than a TV cable, what else do I need for the tranny swap?  Also, my current rear gear ratio is 3.08...I'm thinkin that may be a little high to work out with the OD tranny??

I'm thinkin at least 3.42 - 3.73 rear gears would work best, and still give me better milage than the little 305 which, on its best day can only muster 13-14 MPG.

http://temp.corvetteforum.net/c3/dwaynes69bb/

[VileZambonie]

I would go with the 3.73's with the 700 R4 especially for towing. Make sure you run an auxiliary cooler too. Do you mean the lockup wiring harness? Yes it will work the same.

[d stroud]

Thank you!