vibration problem

-any thoughts on the possibility of the diff causing this type of vibration??? (i dont really know much about these rear ends, never had an issue with a diff before...)
-any opinions on whether or not the d-shaft is still outta wack and causing the issue???

side note; before i buy a new drive shaft im going to see if i can find someone with a "known" good shaft that i can temporarily put in for a quick check. if the vibe finally leaves then it would look like im buying a new shaft...