Mike, See the pic below snapped form a 1951 Chevy Truck Operators Manual which should be the same as your GMC. That is your "fuse box". Fuses are for your "Stop Lamp" and "Tail Lamp" circuits. They are 20 amp SFE glass cartridge fuses for both circuits.
~ Dan 1951 Chevy 3 window 3100 Follow this story in the DITY Gallery "My Grandpa Carl's Truck and How it Became Mine" 1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver) US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)
