If you are going to do it... Take everything out of the newer truck. fuel tank lines, wiring (yes, all of it) and move it over, it will make things that much easier. It wont be that hard but there will be one thing that will need to be modified regardless. The oil pan on the 4g64 does not have the clearance for the front diff so you will need to cut the pan and weld in something to hold the oil in. ... I just finished doing this very thing on my 87 d50 only I didn't have a newer truck to pull stuff from so some thing like my fuel pump and lines are all custom in the truck.