[jagarra]

One thing that you may want to check is your driveshaft angle now that you have fabricated a new cross member and used a transmission foreign to this vehicle. You mentioned it was longer so the angle would have increased. You want to get the angle at the universal close to being the same at the transmission end and at the rear pumpkin. You may have to raise or lower the transmission at the cross member to get an angle that will not induce vibration into the drive system. I think the specs call for it to be <3 degrees, you could check the with folks that did your driveline for their input.