
My 99 astro mark II package has a vibration. It does not start up till you have driven around 10 miles. It feels like it is in the rear and ocuurs beteween 40 and 60 mph. but it does not do it all the time. I thought it was a rear tire problem and had the tire shop check it. They said they could not find a problem but when we got it back the vibration was gone till this past week. It does appear that it is getting worse. I have checked the drive shaft universals and they appear to be tight. I have read on other posts that you need to pull them to check them .I haven't done that yet ,just hoping someone has had the same experience. Thanks for help.