Help!! Engine swap nearly done, tranny won't roll now

I have been working on a 1995 Monte Carlo for the past week and have completed swapping a 3.1 V6 into the car. We got the car running, put it in reverse for a few feet, then back into drive to it's original parked position. After that, we worked on getting the cooling system bled out of air and running smooth. Went to pull the car out and it does not move, runs through the gears fine on the shifter, can see the linkage moving as it needs to on top of the tranny but the car does not move.. can someone please advise where to start with the troubleshooting? Thanks

pull one of the tranny lines off the radiator (make sure you have a catch basin handy or you'll make a mess) and see if you have fluid pressure. You may have a damaged front pump or torque converter if little or no pressure is present.

alright, tried and we have good pressure on the line. The part that gets me is that is worked and now doesn't and all that has changed is we ran a hotwire for the fans to the CC fuse in the box, blew the fuse but have since replaced it and still no dice....

k, now there is no pressure coming from the lines at all. talking it over with a few people we have come to the conclusion that one of the guys helping out didn't fill the torque converter before reattaching it. We then overfilled the transmission to see if we could get it to fill but have not had any luck. I guess the next step is to take it back out and to a tranny shop unless someone has a better idea....

You shouldn't have to fill pre-fill the converter. I've never done it and never had a comeback. The pump fills the converter. It is possible you broke the oil pump shaft while mounting the new engine. I've also saw trash enter the pump, lock it up and strip the splines on the pump shaft.