84/85 swap Question

[Draginjet]

I'll try to keep this short, but.... I bought my son (14 Year old) a 85 4WD SB stepside with 350 4sp manual, no power anything and no AC. Its a nice truck and we were going to restore it as his first truck. In the mean time I found an 84 2wd SB Fleetside loaded, with factory AC, power everything and Auto trans, with a Diesel (yes it is underpowered) and he likes the idea of the diesel (20 MPG). My questions all pertain to what can I swap on these to combine the best of both worlds without major swap issues. We would like to put the Stepside bed on the diesel or maybe swap the diesel engine to the 4WD along with the cab as it has all the power goodies. I'm not sure about the Trans (manual to Auto) tail shaft for the Transfer case if we do this. Is there a site I can visit that has all of the details for what is transferable or can anyone on here help me with what would work and what wont. If I need to post more details of this let me know. Thank you for sharing anything at all is helpful.

[Draginjet]

Or, is everything pretty much interchangeable?