re the launch shudder:
from what i understand, it was simply about angles. although i am not completely convinced, but i am going to have to wait a few weeks to find out as my truck is covered with snow and ice right now. My initial seat of the pants was that the launch shudder was completely gone, but i'm not sure yet. I am going to take it to a driveshaft shop soon and have them inspect all the joints etc.
so far, it is 98% better than it was before.
BTW, my launch shudder was pretty bad.
hope this helps.
Oren.