SOLVED: What size nut goes un stud 2 in fuse box under - Fixya wwwa››Cars & Trucks›GMC›Sierra›2000 GMC SierraJun 14, 2009what size nut goes un stud 2 in fuse box under hood - GMC 2000 Sierra question. Search Fixya. Browse Categories Answer Questions What size nut goes un stud 2 in fuse box under hood. Posted by seleski on Jun 14, 2009. 2007 Chevrolet Silverado 2500HD. 12vlererado stud on circuit breaker under I'm having issues getting 12v power to my 7 way trailer socket. On my '08 Silverado I have followed the other thread here by hooking up the red/black wire to the stud on circuit breaker under hood, and installed a 40 amp fuse for that connection. Still no power. The terminals at the bumper and the connector or very clean.