Stop in for a cup of coffee

Something break in the bottom end perhaps? Or perhaps something broken in the bellhousing area and it's got it jammed? Trans is in neutral with the axle off the ground as I thought at first maybe it'd popped into drive or something

Undo the torque converter to flywheel bolts and see if it will turn over....

If it will turn over, then it's the trans, if it doesn't it't the engine...

Last time I had a jammed crank, the piston hit the valve and the connecting rod was a pretzel wrapped around the crank counter weight...