5.2 5.9 magnum EFI plug and play harnesses

I've not done it, but it should be a no-brainer. the 3.9 is essentially a 5.2 with 2 less cylinders. the harnesses have everything in common but the lack of two injectors. You'd have to tap two wires into the common green/orange wiring in the harness (one to each injector), and run two wires back (one from each injector) into the computer at the appropriate pinout points. With a good wiring diagram (get a factory service manual, not a chiltons/haynes), even an amateur should be able to do it in an hour or two.

Then, just add a 5.2 computer from the appropriate year engine, although I've found all 92-95 magnum computers to interchange and run just as well as the others.