Driveline vibration!!! I need help!

Not sure if you got this fixed, But as mentioned earlier in the thread, I had the same problem. I upgraded my torque converter from an 11" to a 9.5" a few weeks ago and my vibration went away. The 11" was brand new when I put it in but it was a cheap ACC boss Hog 2800-3200 unit ($300). i bought a 9.5" PTC 3600 (was made for a 440 so might be 3800 on my setup) and not only did the vibration go away, It was like I added a 50 shot of NOS to the car. It's Awesome. Hope this helps.