Have a 98 chevy silverado 3500 series with AL460E trans. All of a sudden it will go into gear but doesnt engage. Have put 2 trans in and same problem. Will not move in any gear.

Transmission internal problems. Talk to a good transmission specialist and he may save you a complete tear down.

Have installed 2 trans, Tcase, no dtc's, fluid good. If it was internal trans problem? Why would it still not go into gear after 2 trans. +Tcase? So both trans had same issue? Not liklie.

It grinds because the shaft is turning and then you try to engage the park pawl. Check that the transfer case is in gear, the driveshaft is hooked up correctly and not spinning when in gear.