vibration problem

You do not understand what i said in reply to your "they have to have angle" You need to re-read what i said and then what you said on what that link is saying, looks as though you looked at the pics and the author didn't explain anything correctly.

You said they have to run at angles, you do not know why that is and what the reasoning is for it as does the author of that link.

They do not have to run at angles, and as driveline speed increases the ANGLE MUST diminish.