Join Date: Mar 2007
Location: Kitchener, ON Canada
Diff howl is not uncommon in higher mileage vehicles. I'd bet it's more likey pinion related though.
The 4.0 is proabably mated to the D35, though a D44a is possible, esp if the vehicle is equipped with the towing package. There should be a tag on the diff housing telling you what kind of axle it is.
Canadian Jeep Club Member Forty-Two