New issue. 4x4 was working fine. Now an issue. When in 4x4 going forward in town or highway it works well. But stop and go to back up I get about 3-5 feet and the truck stops like you backed into a parked car. Forward, nothing. Just when I back up. Noticed a slight howl now. Only in 4x4. More howl when decelerating. Leads me to believe front diff. But to stop dead in reverse only? Weird. Truck runs great in 2wd. Could it be a bad chain in the t-case? I mean, front diff wouldn't only bind up in reverse would it? Wonder if my t-case chain is piling up in reverse. 2001 Ram 1500. Auto. Ant ideas?