Disregard my post about the 3.5L pump.

you will essentially need the engine harness from the 603. I am doing the 606 swap into my w124 and I am going to get another harness for the engine and glow plugs. For the glow plugs I need to change the plug on the 606 harness so it can interface with the 603 type of glow plug relay. There is no "generic wiring harness" for this swap.

other than that since you're swapping it into a jeep there will be different connections needed for coolant temp sensor and etc.

I believe you might need the EGR computer from a 603 powered car for idle control, I'm unsure of this but someone should be able to help.