HELP!!!!!

I have a 2003 TT with 115k that try's to lock up when you turn full right or left. Really bad in reverse full turn with creaking and popping from the rear.
I had the dealership change the haledex oil and filter and it had a small amount of debris. Not metal just looked like a small amount of clutch dust in the oil. Not bad for having so many miles. Dealer says the haledex unit is bad and wants a fortune to replace the haledex. I understand how the haledex works but the dealership will not repair only replace.
Im interested to know if this is common and can I keep driving ??? On the lift without power If you turn the rear wheels the front wheels spin. if you just lift the front or rear those wheels spin fine so I know it's not completly locked up. Any of you experts have a clue????? I'm used to my 78 datsun Z and this is a computer on wheels!!!!! Thanks much!!!!!