engine/trans shake when burning out

Grasping at a straw here but.... Inspect the slip yoke on the driveshaft.. check for damaged or broken splines.
If ok, head in for the clutch.

Plenty of angle on the upper bars, all the panhard bar is doing is creating one more potential bind, as Rog mentioned.....

Everthing looks pretty much hunky-dory to me back there. I think 'rspears' made a good suggestion.