Is there a reason to jump to the conclusion that it's in the tranny?
Had the same symptoms in my bros XJ, at random speeds, after hitting a bump, etc. Vibes got so bad that it was nearly uncontrollable, pulled over and stopped, vibes were gone when starting out again. Turned out to be good ol' death wobble.
Try driving around with a passenger, and/or a co-vehicle. When the vibes start stick head out window and observe front end...Wheels may be 'jumping' back and forth, or anything else moving for that matter...
Just my thoughts...But if I'm right, I could go for some good food and football, oh, and the model with cheerleader friends sounds nice too :greg: