Most of the Delco regulators have "6 volts" or "12 volts" stamped on the regulator housing right by the part number. I don't understand why you keep blaming the regulator for the engine failing to turn, however. The only thing it does is prevents the generator from overcharging the battery once the engine is running. An engine will run with no generator, regulator, fan belt, or even if it's missing the water pump, it will run for a short time before it overheats. If you hand crank it, you don't even need a starter.
First, as has been suggested to you repeatedly, turn the crankshaft by hand, or put the truck in gear and push it a little, (gently, don't force it) to determine if the engine is locked up or not. Assuming it will turn without getting into a severe bind, find out why the starter is failing to turn it. There's only two possibilities there- - - -lack of battery current, or internal troubles in the starter. Stop trying to blame everything in sight and running off in all directions. Attack one symptom, and only one, and follow it until you find the cause of the problem. If you're not able to do that, find someone who can think logically and methodically, who also understands how engines and electrical systems work, pay him well, then watch and learn as he/she finds the cause of the problem.
Jerry
