ok it is an 89 coupe with a 3.08 rear with the dogbone still attached. the driveshaft is stock and the t5 is stock. i have solid motor and tranny mounts and subframe connectors that are , it is hard to explain it but the back seat floor boards are humped up like a tunnel or something. the humps are about 2-3 inches high and wide. i know it has subframes i just don't know how they were put in. anybody get what i mean. anyway this was done by a previous owner. that is not the point though although if anybody has any info on how this was done, i wanna know. i had some 10 holes on the back with some viper tires. my driveshaft came off after 3 bolts backed out and one sheered clean off and hit the pavement and my car pretty hard. but there is no visual damage to it at all. i put it on and tightened the 4 bolts. somebody slashed my rear tires(vipers, they are missed, i could burn down for forever every day and i would barely lose any tread.) that night so i put my front tires on my rear and i bought some centerline front runner auto drags with E/T fronts on them for 50 bucks. the first time i got to drive this car after the new rims, driveshaft problem, it starts vibrating at a certain speed and i mean bad, the seats go back and forth a lot. is it possible i messed the driveshaft up and it is not showing any damage or could it be the centerlines need a balancing. will a t5 start to viberate like that if it is getting old too. i tried to balance the rims today but the balancer is broken at my school. any info is needed here. if i need a new driveshaft i think i will go to a junkyard and get one off of a 92 van.