84 GMC Jimmy K1500 tranny swap

[Suicide-D]

I have an 84 GMC Jimmy K1500 with an NP208 transfer case and a manual 4 speed transmission. I have recently dumped a 350hp (estimated) 350 in this and I really have to get the rpm's up too get going. It has a 3.08 rear end. The tranny is a 4 spd, but the 1st gear is really low range and I have to shift to fast so I dont use it. Will changing to an automatic help in this area? I have a turbo 350 I can have rebuilt...What would be necessary for me to mate a turbo 350 to my transfer case? Thanks

[C.Jackson]

3.08's in a 4x4?? Are they factory? That is a really shallow gear for a K series. you're 350 no doubt has an above RV profile cam?? I'ts not going to get along with that gear ratio very well...as you admitted. It needs a little rpm to get to the power. Your problem will be worse if you put an auto in. The clutches will wear out in no time. Shallow gears, high HP and auto's don't mix for very long. Keep the manual, you'll be able to use more of your horsepower the way you want it. Save your rebuild money and invest in a set of 3.73 or 4.10 gears. Your truck will literally come alive and it will be easier on the drivetrain. What size tire are you running? Running a mid rpm motor at lugging speeds will rattle the bearings right out her and hammer the piston heads with preignition. In the end deeper gears are the most cost effective, performance gaining alternative.

C. Jackson