14 liter detroit help

I have several trucks with several different engines. The one that is killing me is this 14 liter detroit. It is in a 2006 westernstar. Since Ive owned it which is 2 years, Ive replaced the turbo 3 times, egr once, the vpod once, the delta p sensor once, the engine wiring harness once, the vpod egr harness once, the injector harness once Also the EMC twice. I also did the resister trick which didnt work until I had the egr high altitude changed so it would turn the egr off at high altitude. After doind all of that it still doesnt work right. The vpod will not work. This is why i just changed all the wiring and put a new vpod on it. I have the actuator unhooked and a bunge cord hooked up to make it run. All I want is to either find out if I can put and old style turbo on it or does anyone know if anyone makes a wiring harness that goes from the cab that is wired for a DDEC5 and hook it up to a DDEC4 so I can simply put a 12.7 into this truck? Or would I have to buy a complete wiring harness for the cab that matches the old engine? My trucks are off road not on the road trucks.