I have a 2004 1500. Its got an open diff out back and i want some double wheel action in its place. I remember going to the chevy dealership last year and talking to a sales rep. He was explaining to me that 2006 and up trucks came with 100 rpm locking diffs. Is this true or was the guy blowing smoke up my a**? If so I bet i could get a newer rear out of a yard alot cheaper than buying one of them truetracs. Someone HELP!