[Kevin M]

I suppose it could also possibly be your power steering belt slipping, but not likely. If you're getting shuddering at low speed, tight turns, it's one of your differentials, probably center, since your front is open. Fluid changes won't affect the center diff, I think the viscous ones are sealed. If the dealer did any repairs to your diff under warranty, then it's still covered. If you paid for the prior repairs, because it was considered collision damage, then technically I think you can be denied, although since they performed the repairs they are supposed to stand behind their work.