Driveline angles: Is 0.5° really killing me?

[SkinnyG]

I've balanced the tires, I've moved the tires on the rim, I've watched the tires on the balancer and on the vehicle at speed on the lift.

I'm also foolishly assuming the driveshaft I had made and balanced was actually balanced properly; I have no way of checking, other than I can physically see that it HAS been balanced.

The trans is rebuilt, with all new bushings. The axle bearings are new. I changed the poly trans mount to rubber.

The engine mounts are poly 4-link bushes, and pretty rigid.

The vibration feels a bit like a "wagging" from the back of the truck.

The fact that it's inconsistently cyclic makes me think it's driveline.

I've chased a similar "wagging" vibration for YEARS in my squarebody and never fully got it resolved.