1999 GMC 2500seira 4×4 6.0 Underhood Fuse Box Diagram 1999 GMC 2500seira 4×4 6.0 Underhood Fuse Box Diagram 1999 GMC 2500seira 4×4 6.0 Underhood Fuse Box Map Fuse Panel Layout Diagram Parts: underhood bussed electrical center, UBEC bracket, engine harness.