Core support wiring harness?

I ran into a road block putting back together my 6.0 build. I had disassembled the core support and refinished it during the engine build. I have been looking at my buddy's 2006 Z71 Silverado, however, short of taking the core support off I cannot figure out the harness.

It is 2001 Z71 Tahoe. I have All Data DIY (factory service manual) and chitons. Been watching radiator swaps, etc on youtube hoping to catch glimpse of where harness runs.

I now have NO CLUE how the wiring headlamp / core support harness attaches to the core support. Any pictures, any tips, any manual snippets, anything would be greatly appreciated.

Got it back together with a LOT of trial and error. Now it seems the fog lights and the bottom inner lights don't seem to want to work.

Also there were two gray clips. I cannot figure out what they attached to before. Picture below. They are off the main part of harness going across backside of the core support.

Aren't the inner ones your DRLs? Test in daylight (with headlights auto off by sensor), in gear.

Oh do you have to be in gear? I had engine off, but on run. Maybe that's my issue. Thanks!

NM... I still didn't turn the engine on, but I put truck to run. All lights would function, cycling through the different settings. However, the DLR still not. Does the engine have to be running for those to turn on?

Yes, in gear, if they bulbs and sockets are good they should light up. Those sockets tend to get overheated and scorch.

I'm going to order new bulbs. I noticed mine were shot... Had a spare one but it didn't seem to work either. Maybe it was shot too. I'm going to order some LED ones and give them a try. Want to swap out the incandescent anyways they just cause havoc on the connector.

On another note. A couple more things I cannot figure out where they go.

#1 there's two gray clips that are on either side of the cable run that goes across back side on core support. I think they snap the one harness to another? But not sure where? Or which?

#2 I had some star bolts that were for the plastic core support where the headlamps attach. There were two for each side. I cannot figure out which spot they were in?

#3 a bit unrelated, the transmission cooler lines run under the core support. Is there something, a clip perhaps that holds them together. The one seems to rub on the frame rail.