A 1976 350 V8 Chevy C10 likely used
AC Delco R45TS spark plugs. However, there's no single "gauge" for spark plugs. The R45TS designation itself tells you the specifications. The critical part is the
heat range (the "45" in R45TS). This indicates its ability to dissipate heat. A higher number means a colder plug (better for high performance or high compression), and a lower number indicates a hotter plug (better for lower compression or lower RPM applications).
To be absolutely certain, you should check your owner's manual or a reliable parts catalog specific to your 1976 Chevy C10's engine and options. The exact spark plug recommendation can vary slightly depending on the specific engine configuration (e.g., carburetor vs. fuel injection, different compression ratio).
