Only 10 volts at the small terminal, that's a bit strange..
That tends to make me think there is some stray resistance in the wiring between the starter relay and the starter itself, but it should still be enough to operate the starter motor.
I would attatch another wire to the small terminal and run it up near the battery.. It would be best to fuse it if you've got a fuse holder laying around.
Jump it to battery positive and see if the starter cranks over.. Just make sure the truck is in park + parking brake set so it doesn't take off on you. Be prepared to quickly pull the wire away, if there is a short in the starter it'll get real hot, real quick!
If the starter won't operate by jumping it like this, the new (remanufactured?) starter has gone kaput on you (assuming the truck batteries are fully charged) because at this point your elimnating all the truck circuits.
It's not uncommon for reman starters to fail in short order like this, they tend to bench test them, but that doesn't put an real load on them (like your Cummins engine does anyway!). I suspect you've got a new, bad part. Take a wooden hammer handle or the like, and tap on the starter solenoid while a helper turns the key, it might 'jar' it back into existance enough for it to operate.
Try it and let me know the results.