No marker lights/ license plate

02-2500 24v. All lights work except marker and license plate.

I know there's power to the rear as blinkers/hazards/brake/reverse all work. I also have power to the trailer plugs.
Replaced the headlight switch
Replaced the blinker/hazard
Replaced all lights
All fuses and relays are good
Replaced rear abs sensor
Also replaced stereo deck
All my dash lights are fine

I'm coming to the conclusion that I either have a grounding issue or it's the fuse box/tipm. Does anyone have any experience with this or advise on what I should be looking for? Thanks