i have a 90 f350 wich had a 5.8 and got a 95 5.8 out of an f250. the wiring harness on my 90 has 4 seperate plugs for the engine wiring, the 95 has 1 square plug. is there anyway to splice the two? does anyone have a diagram that i can use to decode the difference in the two harnesses?
thanks in advance!

 

You could splice the two, but you are talking about splicing dozens of wires together, counting on the wiring diagrams to be 100% correct, counting on you not making a mistake, and that's not even touching the problems that are going to come down the line when the splices you make might start corroding and intermittently failing.

It would be better just to use your existing harness the '90 F350 came with and just plug the connectors into the correct sensors. If you have to swap a couple of connector pigtails do it but you will have far fewer problems this way.