Engine replaced - now, transmission dead, noise?

[Dcurbet]

Puzzled on this one, replaced engine didn't really touch the transmission other than pulling the torque converter for a second (thought a washer fell behind it) and that was it.

Now put it back together and there is a racket (uniform) coming from the transmission. Won't engage into any gears. Oil is good, lines are connected.

What could have gone wrong?
I highly doubt the transmission failed over the 6 months it sat with no use, it was shifting just fine prior.
2001 qx4 with 180 K.
Help.

[Towncivilian]

Welcome to NICO.

Could you post a video of the noise? Does the noise persist in any selected gear (P, R, N, D)? What color is the fluid? Does it smell burnt? Was the transmission serviced regularly?