Nasty Vibration

[coralcoupe1993]

Before I start rebuilding my T-5, I want your opinion. My 91 Vert has a nasty vibration. It comes about with the combination of RPM and mostly speed. 60 mph+ it has a vibration. Usually 4-5th gear 3500-6000; from 6000-6500 the vibration stops (yes I rev it that high, yes it has an ford rpm extender). It isn’t the drive shaft, I put a different one in. I don’t think it is the tail shaft because the rear seal isn’t bad. What are the chances that the fly wheel is out of balance or clutch may have lost a bolt? I know it will only take a few hours to dig into this but I would rather see if anyone experienced this?

[INSANELY CRAZY]

could be the harmonic balancer... check to see if the little rubber seal is coming out in the front.. reving to 6k isnt to good either could've scared a bearing.. just some options to check into

[coralcoupe1993]

could be the harmonic balancer... check to see if the little rubber seal is coming out in the front.. reving to 6k isnt to good either could've scared a bearing.. just some options to check into

Well it is only when It is moving and up to speed. Not just sitting still (that much).