VR30 7AT Swap Vibration Issue

kfcgodsword

My fellow 370z enthusiasts, I need your help.

Recently swapped in the VR30 7AT transmission so I could eventually supercharge my Z and not have to worry about the trans as much, but I've run into a problem that my shop and I can't seem to diagnose. As soon as I get up to around 60/65mph my Z starts to vibrate pretty bad. So bad that I can't even really use my rear-view mirror because of it, and it's quite audible. When I did the swap, I bought the aluminum Godzilla Raceworks drive shaft, SOHO transmission mount, and also put in a LOJ flexplate. I had this all done at a reputable shop but it was their first time doing this specific swap.

My instant thought was the driveshaft was un-balanced, as I saw people report the same vibration, and that was the culprit. I had my shop remove the driveshaft and had it sent to get balanced, but according to their testing, it was balanced. They did however say that some of the "tolerances" were maxed out on the driveshaft, but honestly I don't know what that means. At this point I'm still not convinced of the driveshaft's quality, and I'm thinking this may still be the culprit. I talked to someone on reddit who did the same swap in their G37, and he had a similar issue, and was guessing it was either the driveshaft or the mount. SOHO says their mount has polyurethane on it to reduce drive line vibrations, and its made specifically for this swap, so I'm not sure. I had already bought the driveshaft from Godzilla when I saw that SOHO offered one as well with the mount, and at this point I'm almost wondering if I should just bite the bullet and try theirs out to see if it fixes the problem.

Obviously no one wants their Z to vibrate once they get any sort of speed going, so I wanted to see if anyone here had any insight/advice before I do something stupid and spend more money. Any help would be greatly appreciated.