Having the wiring breakdown the underhood box will help. I did a lot of hunting and pecking to find which fuse went to which relay, etc.
The yard that took my engine out gave me a lot of "pigtails" on the bottom of the box. They did not cut the plug that went to the engine or PCM, but everything else was cut about 2 inches from the plugs underneath. I spliced each of the truck wires to the pigtails to make the fused and relays work.
So if you're looking for exact connections, I didn't document. sorry. I know this will one day come around and bite me in the @$$.
However, in another thread I saw this aftermarket box. I think this would have been a better option than the underhood block.
https://www.michiganmotorsports.com/...0aAmpDEALw_wcB