[bikernut]

I purchased an 2003 GMC 3500 standard cab 4x4 with a dump body. I have been having electrical problem from the start in the rear over the dual fuel tanks. When they did the dump body they hacked into the rear harness on the frame and I do mean hacked as it didn't come with a trailer wiring outlet so they made one and hooked up the body lights ( stop, tail, directional, and backup) they removed the tail light that came with the cab & chassis and added there own that came with the body. to cut to the chase here what I would like to do is replace the harness that runs down the left side frame with one that has the trailer harness incorporated into it and goes to the junction panel on the rear cross member and the I can make the correct splicing with soldier joints not those damn splice connectors and doing this on the trailer wiring harness I had on my other 05 pickup to go to my bed up by the cab for a fifth wheel that plugs into the factory harness at the rear bumper. does any bode know where it connects on the from of the truck and runs the length of the frame to the rear, and what about the part # for this as my truck at the dealership doesn't show a parts as my truck didn't come with a trailer hauling package? does any one have a wiring schematic for a 2003 GMC/Chevy 3500 cab and chassis with dual fuel tanks that I can understand?
thanks for any help