I am not sure that the angle of the tranny or diff is all that important
What is important is the angle from trans to shaft and shaft to pinion.
These two angles need to be very close
I think I read somewhere that about 6* is the MAX working angle for a long wearing joint-----and probably about 1* min (the joints need to work some)
I think I am having propshaft issues myself---seems all the information I get on driveshaft angles only apply to one piece shafts. My 59 Elky is a 2-piece.
Adding about 10" to tranny length with the TKO really screwed up my angles.
I'm getting a shudder at about 60----very slight, but there.
If anyone can locate info and extremes on a 2-piece---I'd appreciate it.