04 Silverado Z71 4x4

I have an 04 Silverado z71 4x4 with a leaking driver's side axle...something! I've had the seal replaced 3 times, as well as the axle shaft itself replaced once and that was recommended by GM I've been told GM has changed the design of the seal and that is causing the problem...Is there any truth to this? I had the dealership where its being looked at replace the new seal with one of the older seals (they found one) and they tell me if this doesn't work the differential housing will need to be replaced?!?! Is there any truth to this?? They also tell me they have never seen this happen before (I find that hard to believe coming from an authorized Chevy dealer/servicer)

Any advice out there? (Other than find a new service shop cuz thats gonna happen rergardless)

Fishinfooleric10@aol.com

well I have a 99 and had to get mine replaced about a year and half ago. Knock on wood I have not any problems since. So yes they do leak because this is one of the only things I have not fixed myself and my mechanic said this wasn't the first one he's done. As far as having to get the housing replaced I'm not so sure, but hopefully my little bit of info is helpful.