First off Ihave a 91z28 with a T56 in it and have put the Spohn T56 crossmember in it. Now here is the problem:

I have been trying to track down a vibration problem in my car and I am 99% sure I have tracked it down to the NEW Spohn T56 crossmember I have. Once the crossmember is bolted up to the car and I start it up and rev it, the car will vibrate. the dash and steering wheel shake real bad and so does the console. the cossmember I have is part of a built in safety loop and torque arm. If I loosen the bolts on the crossmember and tranny mount and leave the tranny where it should be with a jack, the car will not shake at all I cant figure it out at all. I have checked to see if the crossmember is touching anywhere and it is not. What can be causing this. I did remove the tranny and put a new flywheel in and then started the car and it revved nice and smooth. I then put a new SPEC clutch in and started it and I picked up a slight vibration for a few hundred RPMS around 2000 but thats it. I then put the tranny in and here I am now with this problem. It is NOT the input shaft ( I dont think), when the car shakes I push the clutch pedal in and the shake is still there so that is how I dont think it is the input shaft. someone please shed some light on this please.