2000 3500hd factory cab marker lights don't work

[2000 3500hd]

I bought a 2000 chevy 3500hd flatbed and the cab marker lights don't work. They look to be factory and I can't find any fuse to run them. I sent power up to them from the battery and all of them came on so I know they work. I can't find any kind of schematic or any info to show how they're wired or what fuse they run off of. Any help would be appreciated I'm going crazy. Thank you in advance

[2000 3500hd]

as of now looks like we got it