Vibration in drivetrain

I have the same type of vibration that has been going on in my scamp since i bought it in 1997...but mine gets worse the faster i go up to a certain point at that point the vibration gets better until i let off the gas then the vibration comes back but way worse...the vibration i have pulsates and resinates through the whole car. The only thing that is left unchanged from 1997 is the front spindles. Please help!