I recently put a new (rebuilt) driveshaft in my car from Driveshaft Specialist Inc, out of TX. My car has roughly 500,000 miles on it (drove for about 1.5 years with broken odometer, putting about 1200miles/week, so not accurate). I had a nasty vibration between 58 and 72 - the one that hits you in the seat of the pants. I "thought" that it wasn't bad at the other speeds, man, was I wrong. After having the new shaft put in, I am absolutely amazed at the difference in my car. It is as smooth as glass - I guess how it was designed to be. I don't think that it has EVER been this smooth in the 10 years that I have owned it. If you have seat-of-the-pants vibrations, don't hesitate, get a new shaft and enjoy!