Interior and lights wiring.....

I am new to this conversion stuff and have tons of questions. Any info will be greatly appreciated. I am swapping an 02 6.0l into my 99(obs) that had a 6.5l diesel. I am going to order a harness from nelson for the engine. My question is this, on the wiring in the truck that was not used to run the engine, like all the interior stuff, and exterior lights, can this be used still? I guess what I am asking is if this is on a different circuit that the engine was? I am no electrician, but I do know the basics of auto wiring.

The cab and chassis harness will remain intact, the only harness that will be removed and trashed is the engine and some of the trans harness.
In order to get your gauges working, you'll simply tap in to the new harness.

The voltage and fuel gauge will continue to work, our harness will have two wires for the tach and speed to use.
The watertemp gauge, use the passenger side head to install a new water temp gauge and take it directly to your cluster, or use a '98 three pin temp connector and sensor in place of the ls stock one.
Oil pressure, tap the block somewhere and use your stock oil pressure gauge from the diesel.

good luck and let us know if you have any questions,
allen

What about a/c, head and tail lights and stuff like that?