Chosen Solution

I installed a rebuilt transmission from a reputable company along with a used (freshen up with new seals) transfercase and new standard torque converter. I put a quart in the torque converter before install, 6qts in the transmission before startup. I ran the engine till warmup checking the fluid in the process. I moved the shifter through all the gears and back. When i went to put it in park sounded like the transmission was rotating because of the grind on the parking pin. My question is the truck does not shift into gear either forward or reverse could it be the transmission or transfer case? Do i need to readjust the TV cable? I double and triple check all connections.

@dgrenon, Make sure your transfer case is not in neutral. The reason you get the grind when you try to put it into park. If the transfer case is in gear, then there is something wrong with that; not the transmission. Without the wheels engaged via the transfer case, there is nothing to stop the rotation inside the transmission so that you can put it into park.