OMG! that was the same thing w/me. the moment i turned on the ignition after the axle job i noticed the vibration.Jetdoc said:If the knuckle is not put together correctly and is too tight the vibrations will be transfered to the engine instead of being absorbed. The axles should "float" between the wheel hub and the differential.
It didn't make sense to me either. I put another reman axle in myself and it cured my vib. What was so strange to me was the vib in park. I noticed it immidiately the first time I started it up after a shop put in an axle I bought.