Drivetrain 2002 3.8, Automatic Transmission Will Not Engage

Just did a motor swap. Everything is installed and bolted up, except the transmission will not engage now.

The linkage is connected and I have verified that it is shifting, however it does not engage when shifted into gear. The engine RPMs sound like they drop slightly when I shift it in gear but I don't feel it engage and of course when I press the accelerator... It does not move an inch.

I am thinking it may be the torque converter (maybe needs fluid). I did not empty it and checked it before I put it back in.

Any suggestions?

Thanks,
Joe

Here's some additional information on the problem. I put it up on jack stands and drained the fluid from the tranny. It's smoked, darker that normal and smells burned. The magnet has a fair amount of debris on it as well.

My guess is that this is not a good situation.

This is new territory for me, anyone have advice on next steps? Am I going to have to pull this thing and have it rebuilt?

Thanks
Joe