Trans??
 

The beast has been difficult at times to get into first or reverse right away when it's cold. You really have to push it to get it in gear. Today, in reverse, it made a horrendously frightening grinding noise when I was backing up when it was cold. I'm going to check the lube levels and rear diff fluid tomorrow. Please tell me there is probably a simple fix (like the IAB when the throttle was sticking- thanks again). Any ideas are appreciated.