I don't have the right words to describe it but it sounds as if you insert a piece of tie wrap onto your aux fan while it spins. It rattles and some occassional "thug" sound. This is what I experienced driving to work last week and I did not get the same noise driving back home. It seemed to be coming directly below the shifter. The last I did was replace the motor mounts. Also, the tranny mount was replaced 3 months ago. What could be wrong this time?