Lots of wires on a PSD vs IDI for sure. 7.3 CCLB dually with a 6 speed is a sweet rig, I think it's worth the effort. One thing that I would pay a lot of attention to is any updates/differences between 99-03 that might effect the harness options. If you can identify the correct harness for your truck and confirm with a diagram, then try to verify what newer/older harnesses differences are, it will help your search. I think you can still get a brand new engine harness from Ford and although it seems expensive, having all new wires/plugs/clips has it's advantages. Good luck and hang in there. Harnesses/interior work is tedious and detailed, but organization and taking your time should pay off in the end.