Vibration over 65mph

So while I was trying the suggestion of turning the driveshaft 180 degrees to see if that would help the vibration, as I was getting it up to speed, my head gasket blew.

I had a bunch of stuff to rebuild the top end (heads, cam, intake) and it looks like I will be doing that instead of figuring out the vibration! At least it’ll be more fun than trying to find out my driveline vibration.