What size gas tank is in an 1983 s-10?

The fuel tank size in a 1983 Chevrolet S-10 varied depending on the body style (regular cab, extended cab) and options. There wasn't a single standard size. You'll need to check your specific vehicle's documentation (owner's manual if you have it) or look at the fuel tank itself (often stamped with the capacity) to know for sure. You can also check a parts website using your VIN.