I let my brother borrow my manche yesterday ,he told me the truck felt like it had a flat intermittantly and he said while it happened his girlfriend (driving behind him) was able to see the rear wheels moving side to side? I'm assuming my diffs on its way out, have any of you guys experienced this before? this has happened to me before also and it happens just for a few seconds maybe a minute tops then goes away. 89, 4.0/AW4,2WD,D35,short bed