The truck stalled as it was being parked, and when trying to restart the engine would not crank. I could hear the starter solenoid click but nothing after that. Took the starter off and had it tested. Test results showed failed starter. Replaced the starter and engine cranked right up. Runs as normal, but when I put it in gear, the engine revs but no movement or feel of the transmission engaging. Visual inspection shows the linkage arm moving as normal through all gears. Any ideas where to begin diagnostics would be appreciated.

 

Could be a torque converter issue, that can cause a stall if it didn't release when slowing down
And now it won't engage
And you tested 1st and Reverse

Check trans fluid level engine OFF
Then recheck engine ON
Level should, of course, drop when engine is idling, i.e. pump in transmission is working
All automatics run on fluid pressure, so no pump = no GO

Torque converter is a type fluid coupler so as engine spins main section the other, internal, section connected to the input shaft try to spin as well, if you are in gear then input shaft should have enough force to move the vehicle
If tor converter breaks then no movement at all