1979 Chevy Truck wont start/no spark

Welcome to the forum. Is the coil in the cap? Check the small primary terminals going to the cap, pink wire goes hot when you turn the key on, no crank. The other terminal is usually tach, if you use a testlite on the tach terminal, engine cranking, the lite should pulse? Does the rotor turn when you crank it? If all that check out and no spark at plugs, I suspect the cap or rotor. If it is an external coil, the coil wire could cause a problem.

Do you have battery voltage going to the coil, all grounds checked out-also check if the cap and rotor are making good contact