I know its an old post but just in case........ A tuned port injection setup out of a 80's IROC Z is also a 3 wire hookup. not much to it. If you want to go TBI out of a late 80's early 90's truck, try to pull the entire harness as 1 unit. The fuel pump relay and sender run all the way to the back of the truck. I started this setup (tbi) on my old XJ and its just a lot of wire to deal with. There are alot of unused wires that are not fun to make look halfway good. You can get a custom harness built with only the wires you need from painless or a coupl of other companies.....that would be the easiest but $$$$. Painless is usually the highest cause you pay for the name. They know their sh*% though. TPI is by far going to be the easiest but that Cummins sounds awful cool. If your motor is good you can just swap everything from the intake up and hook up the 3 wires. I'd like to find a Cummins to put in my ol dodge RV,make a tow rig out of it. Good luck. Tim
