Drivetrain Vibration

I KNOW IVE said this before but,i had the same issues as you.i had 2 diff. shops balance the shaft,several u joints,still had a vibration`.new shaft from strange engineering and vibes were gone.might be something to look into. also if your trans is 3 degrees up towards the rear,the rear should be set at 5-6 degrees down.as per cass at dr diff,thats with standard springs,