I have been reading some older threads regarding changing the Differential Fluid. A few people mentioned that the service manual says to change the differential fluid at 3,000 miles if towing. My 2006 service manual says to change the differential fluid at 30,000 miles if towing. Has there been a change since the 2004 model? Are they now putting Syn Fluid in the 2006's? Or is there some other service manual out there that says to do it at 3,000 miles?

I went through and changed to synthetic on all mine (Trans, diffs, transfer case) at my first oil change. They use a sealer on the gaskets that forms gunk that hangs out in the bottom of the diffs. I wanted it cleaned out. They changed the weight in '05 but never went to synthetic.

The 04 manual says 3000, which I am will to bet is a misprint and should be 30k.