When Im in 4WD I start to get a clunk from I think the front end, but it also feels like the rear end. It only happens in 4WD. Its like going over small bumps but theres no bump in the road. The vaccum motor is and has been broken, I rigged it so the front is always locked in. It cant be the vaccum motor, transfer case?, front diff?, axle? Any thoughs??? Thanks