Originally Posted by Tyson
Ya know, there are a few bells ringing in my brain now.......I should have looked deeper. This spring, gas mileage dropped from it's normal 13mpg mixed driving down to 9-10. Even after a tune up of plugs and wires it didn't change. I shrugged my shoulders at it and went fishing.
I bet the rear end has been machining away, creating drag, and slowly detonating this whole summer.
If anyone else is wondering, the shop said the diff fluid was full, but obviously contaminated with metal.
Edit. I do believe ratio was 3.73, but can't swear to it, trans cooling is whatever the factory trailer/towing package came with. I dunno, I had always heard the 6.0/4L80 combo was as bullet proof as it gets. I've never personally known anyone that had a differential failure. None.
I was wondering, if mpg had been dropping, giving a warning sign. Problem is, the diff is probably about the last place one would look for a sudden mpg drop! I guess it all comes down to "it happens".