So I'm putting in a new transmission, and a new torque converter. Nothing special, just stock replacement from O'Reilly's. Problem is, I can't actually get the converter all the way on. Bellhousing bolts will start, but can't actually torque it down. Any suggestions?

Rotate the torque converter until it fully engages the pump.

Turned out to just be a faulty converter. Got a new one on the way.

Don't forget to get the correct spacing between the converter and the transmission input shaft bearing. Too much, or too will damage the pump.