i put my truck on a lift and ran it and noticed that the driveshaft wobbles. Could this be the reason why im getting a vibration around 55 mph? should i replace it?

 

check your u joints first.. and my way to check the driveshaft is take it off and roll it on a flat surface.. and if it has a akward roll even slightly... toss it... driveshafts are supposed to be prtty much traight.. if you look on your driveshaft you should see a little weight to help vibration purposes...

 

well i know what the deal is. I took the drive shaft off and put it back on and the problem went away. The driveshaft wasnt centerd perfectly at the u-joint so it wobbled.