Thanks to bobn's assistance, and others, my driveline vibration problem has been fixed...good enough, at least.
This weekend, I installed the D&D double adjustable upper control arms and did a few test 'n tune runs. I ended up setting the pinion angle to 1/2 - 1* negative.
Before, I couldn't get the car past 115mph without rattling my freakin' teeth out, starting at about 100mph. After setting the pinion angle, I got the car up to 130mph before having to shut it down. I could have gone for more, but there was an obstacle in the middle of the road(car).
I think the fix was a combination of the carbon fiber driveshaft and the control arms. There was still some vibration, but it seemed like the chassis was vibrating before the shifter this time. And it never got to the point that the car felt like it was going to fall apart, as it did before. So, I am very happy!!