No, it’s not the main fuse block. You can see part of the bracket and the relays and hazard flasher in the picture. I read they call it a convenience center. It’s tied into the wiring harness
I have an ‘85 c10 standard shift that I’m restoring. A body guy completely gutted the cab and I’m reassembling it. I can’t for the life of me figure out where to mount the “convenience center”. It has the hazard flasher, a relay and something else. It has a bracket and two mounting holes...