Hello,

May be a stupid question, but would a 4 speed (OD) tranny from an 89 K1500 be able to replace a 3 speed in an 89 K2500. They are both 350 engine, though I would have to look into more specific info. Just wondering if it is an obvious yes or no.

I wouldn't see why not. Does the 89 K2500 have an electronic speedometer or a cable driven one? I don't think that you will have any troubles with this as long as the 3 speed has a lock up TCC. And also if this is a 350 turbo trans (3 spd.) I think it has electric kickdown, the 700r4 (4speed) has a manual detent cable.