I know this is the 1987 and older side of threads but i drive an 85' k20 with a 96' 350 vortec swapped into it and a 4l60e. Correct me if im wrong but I believe the year of my motor was built off of the same small block 350 used in the square body chevys. The 4l60e thats in the truck now has a few issues such as i have to use a dakota digital gps speed sensor for the trans to shift because the speedometers used on 96' trucks are different from the 85' trucks, and for whatever reason i can't shift into 3rd gear manually. I'm fed up with this trans after battling shift solenoids and all the linkages being screwed up and the fact that it just does not cooperate, so ive considered doing a manual trans swap, the truck was originally equipped with a 350 sbc and 4 speed manual but since the motor swap (which i'm the 9th owner according to the vin, and i was not present for the swap) it's had most of its manual trans pieces removed such as the clutch pedal and there's a hole in the floor patched with sheet metal. I've researched manual trans swaps for this motor and ive seen nv4500 swaps and t56 swaps but i was wondering if the same type of trans originally in it (not sure of the name) like the 4 speed manual would bolt right up to the 350 vortec out of a gmc k1500?