Not to long ago we aquired this great truck. The front diff. was wet and the axle seals were leaking. We choose to do a quick change out of the diff. & went ahead and obtianed a good used one and changed it out. With in a few days the new diff began to show the same visual wetness (in just 2WD) Because I do not know how this 4x4 system (auto) works, I wonder what be the cause? I have check the vent tube and it is clear? I have driven it at Hwy speed in auto 4WD and it looks worse. Anyone who knows the issue and can help, please communicate as I really enjoy the truck. Thanks to the two who replied thusfar. If anyone reading this knows how the 4x4 sytem (c/w auto 4x4 switch) works with this truck & that might have an idea or two on this problem. Please feel free to reply, as any help will be greatly appreicated. Rumor has it that there are clutches in the transfer case. Could this may be the issue?