My brother-in-law has a 2007 Sport Trac, V6 4x4 and it needs a rear drive shaft carrier bearing. He was told he needs to buy a complete drive shaft because the carrier bearing on 4 wheel drive models is not serviceable. Is that true? When I do a search so far I can only find carrier bearings for 2 wheel drives so I guess it could be true... Looking at the one on my truck which is also a 4x4 it sure looks damn similar to the photos of the 2 wheel drive carrier bearing that everyone does sell. Also, is there any difference between V6 & V8 rear drive shafts if it is a 4x4? It would make sense to me that the rear shaft for a 2 wheel drive would be different because of the 5-speed vs 6-speed transmission but if all 4 wheel drives use the same transfer case then I would think the rear drive shaft could be the same on all 4x4's regardless of which engine it has. ????