i notice with my antispin 2005 CTD 4X4 it kinda turns crappy on dry pavement when making right corner sharply.

 

Sounds messed up to me
I have had lockers in many cars and trucks factory usally work really well till you beat the crap out of them! These trucks have Sterling or AAM axles and both are really good pieces!
Hit the dealer and see what they do
I bet they put a new one in if its under warranty