no start, HELP!!

[mudgutsandglory]

hey guys ive been working like mad to get the new motor in the '82 GMC fired, and after all the thrashing i have a no start, i dont even get a click at the solenoid, so...i ran to the parts store and got another starter, same mess...
i think im missing a wire, but i cant find it!
here is how i have it hooked
there are 3 terminals on the starter
the first terminal,(from left looking from front of truck) is marked R, and i have nothing on it...
the second terminal is the main and i have the main hot battery lead and another ring terminal that has two like 10 gauge wires hooke to it on that terminal...
the 3rd terminal is marked S, and i have a single wire with a small terminal hooked to it...
for some reason it wont crank, i think im missing a wire, and im worried like crazy
please help
later
Dan