Pretty much like the title says. I have a fresh rebuilt T-5 and rear end. This was happining before i did anything to the drivetrain and i figured it wouldnt happen anymore but it still does. What happens is once i get to over 60 if i dont have my foot on the gas the vibrations will surge untill it gets back down to 60 or i give it gas again the higher the speeds the harder the vibrations. I thought i had seen something about this in some fourms i dont know if it was this one or not. it even does it if im over 60 shifting out of 4th into 5th as long as im not giving it gas it will do this clutch in or out. Anyone have any ideas or this happen to them?