We did a motor swap on my 94 k1500 4.3L and used a motor from a 89 s-15. Now we are having problems with the transmission. Our main question is if the torque converters are different- the s-15 was a 2wd and the 94 1500 is a 4wd. We can feel it click into gear but the truck doesn't go anywhere. The shaft was spinning because it grinded when we put it into park.

 

converters are the same, maybe its low oil level