Just about any late '80s through the 90's v6 or small block 8 will drop right in without too much alterations. Hoses and wires to different spots but not too far off. The bell housing should line up fine with your tranny. It's a truck so there's a lot of room to play. You could get an old galaxie II in a bone-yard for peanuts with a good v6 in it. The block will fit in the frame of your truck. The exhaust hookup would be a challenge but doable. You could go big block too if you want to hot rod it. Lots more work though.
