Ok I'm new to this forums, and I want to ask a quick question to make sure. When i accelarate from a stop i get a really bad vibration on the rear and beneath the drivers and passenger seat. I was hoping it could be something to do with the driveshaft or rear end. I'm planning on installing 3:73's or 4:10's if its the rear, but im hoping is the driveshaft. Oh by the way is a 1997 mustang cobra. Any help is appreciated thx.