I have an 03 1500 with the 5.9L gas engine. The 1st engine threw a rod out of the oil pan. The 2nd engine has a spun bearing. I'm getting ready to put a 3rd engine in it. Before this engine spun the bearing, I was tracking down a miss. It had several codes for cylinder misfires. I guess that this is a common thing from reading the internet. However, I think that I have it narrowed down to an improper voltage signal involving a relay. It's not the relay. I'm not sure if it's the wiring or the fuse box. I took all the plugs off the bottom of the fuse box and soaked it down with WD40 in an effort to clean it. Didn't solve the problem. Anyway, my question is are the engine wiring harnesses that go to the ECM all the same or do I have to find an 02/03 with a 5.9 like mine? Also are the fuse boxes the same.