Okay well originally i was experiencing a vibration right beside by my right leg. It sounded like the motion of the drive shaft because it would go louder and quieter in a circular sort of fashion as if something rolling over. I had originally thought that it was my trans mount bushing because id only get the vibration over 4000 rpms. Now the problem has worsened. It seems fine when i first start it up and start driving but after it warms up i start to get the vibration at 70 kilometers and it gets worse and worse when i try to accelerate. I also get a slight whirring noise coming out of my back end. I checked the trans mount bushing and it still appears to be in place. What else could this be? Maybe an unbalanced drive shaft? This problem occured after a good day of driving it pretty hard (nothing stupid though) so im assuming i broke something i just cant figure out what. Anyone have any ideas? if so how do i check for the problem? (for instance i have no idea how to check if i have an unbalanced drive shaft). Thanx for any help i really need to get my car back on the road.

EDIT: what should your tranny mount bushing look like? In the magazine i have it looks like the poly one has a stopper (umm like the rubber piece just poly) on the top and on the bottom...mine only has one on the bottom i think it looks right though. What should it look like?

 

Check the ujoints for play.

 

Did it ever make a noise ?, U joints like to squeal before they die and leave your driveshaft on the road.
Im not sure how it is on a stock camaro shaft as ive never had a problem with mine, but on my blazer I would have to have it balanced twice a year because of the abuse it takes four wheeling. It has weights that are tacked on, similar to balancing a tire, that it would loose.