defiance

I was going to be really disappointed if the aluminum drive shaft did not cure the vibration, seems to be hit and miss and depends on other factors other than the drive shaft it self. It is one mod that I am really looking forward to. As far as the slop goes, wish it would help, but I guess its just the nature of out drive train.

SteveB_RET

Pinion angle is critical with this DS. When I installed my DS, I also installed a new upper control arm and had terrible vibrations above 80 mph. What it ended up being was the wrong upper control arm. The store had a lowered car upper control arm marked as a stock OE replacement. I went back to the stock upper control arm and no long have any vibration issues. So bottom line is if you have changed the ride height of your car and do not have the pinion exact, then you will have vibration issues with the one piece DS. I have had my Stang up to 130 mph now with no issues.

808muscle

Didnt realize I never updated my thread. Got a new DS from shaftmaster, installed it with an adjustable UCA. Had small vibrations so I starting messing with the PA. Could never find the sweet spot. Was literally making changes after each run at the track. Could not dial it in. I had several 9 second car guys check it out and they were dumbfounded as well. I adjusted the PA over a dozen times, nothing worked.
I have read that automatics can have this issue. IDK.... Gonna take it out. Car was never faster at the track which was just as disappointing.
Shaftmaster has been great during this entire ordeal so don't think I am bashing their product, I am not.