You need a Poly-U "Tranny-Mount" bushing set.
I have a prothane set.
There's one small problem, which I won't go into, but the NEW Re-designed Energy Suspension Bushings have fixed the only problem I've experienced w/ my Prothane kit.
Contact Tony D at NewEdgePerformance.com (You can find his link on the front page of Focaljet under the "Resources" link.
)
Tell him you want the Updated Energy Suspension Tranny-Mount bushings, and tell him I sent you.
That will totally Stop what you're describing.