lost the positrac clutches in our 2001. 5 3500 last week, took a week to get the whole unit replaced due to shortage, obviously, they have had problems here. when i say "they" i mean dana and dc. mechanics told me that this was right behind the fuel pump problems in heavy towing trucks. the first sign is a popping and squeaking noise, then as it goes there is a bad vibration, i firts thought of a broken shock, flat inner dually tire. the whole unit is replaced as a core, kind if like the old gertrag trannies... .