[pkviking]

I noticed some quite play in the rear U-joint, so I took the drive shaft to a shop to replace the U-joints and get the shaft balanced. There was no vibration before but I thought I should get it fixed before it fell off http://www.allfordmustangs.com/forum...cons/icon9.gif . But after I mounted the shaft I noticed a vibration that starts at 45-55 mph. The vibration goes in and out once a second or so. Is it important to mount the shaft in the exact same possition, both at the transmission end and rear end? The shaft is a two part with rubber bushing towards the rear end. The shop says that I'll have to get it rebuilt, but I don't understand that since it realy worked ok before. I read that the rear transmission mount could cause vibration?

[72 fastback]

I had mine vibrate terribly many years ago and had a once piece design made. Cj pony parts sells them complete.

[Ponycruiser]

Whenever I remove a driveshaft, I always mark it so it bolts back up to the rear axle the same way. It sounds like the DS is 180* degrees out.

[pkviking]

I did rotate the shaft 180 degrees and the vibration got a lot worse so I'm sure it's mounted correct to the rear axle. Are these 2 part shafts known for vibration? Has anyone had their shaft rebuilt (new bushing)?