Honestly, at this point, I think I'm going to adjust the AHC sensors to bring it a bit lower and see if I can get the vibration to go away with height changes. If I can, then I might sink some money into upper links. I'm north of $1000 chasing this issue and have nothing to show for it; I'm not keen to spend much more throwing parts at it.Adjustable lower arms won't really change the diff angle much; not enough to effectively correct the pinion angle: the adjustable RLCA are mainly for positioning the axle forward or rearward. The adjustable upper rear control arms will have the greatest impact on pointing the diff up or down and require much less adjustment range to achieve measurable pinion movement. Your goal is 1~ 3 degrees of offset between the output flange and the diff flange ( like this /---/ ) . Ideally 1 degree is optimal; that is 1 degree difference: for example if output flange at TC is 1.5 degrees down, then the diff flange should be pointing UP 2.5 degrees (2.5-1.5 = difference of 1 degree)- this would require lengthening the rear upper control arms to achieve getting the pinion to point upward. Anything more or less than 1~degrees puts more stress & wear on the ujoints and will present vibes at various speeds.
Having adjustable upper & lower arms together is best option to dial in your driveline. As you lift the rear end the axle can shift where one wheel is slightly more forward than the other and also lifting the rear will point the pinion downward. (The axle also shifts to one side affecting thrust angle but thats another mod with rear adjustable panhard).Anyway, if both the TC output flange and the pinion flange are pointing downward ( /----\ ) then you'll start getting a growl, vibration etc. The Toyota ujoints are pretty forgiving, but on older drivelines you'll notice the misalignment is more pronounced. I'd recommend the "on vehicle" adjustable uppers that TT makes which are adjustable while connected to the truck, vs. the remove, adjust and reinstall type. It's much easier to adjust them while connected to the driveline- no removal required.
Edit: Just did more reading and damn is this a frustrating subject. I think it's possible that my lack of rake is a contributor to the problem as well, as that changes the pitch angle of the driveline too. Guess I get to spend saturday adjusting links and AHC to see if I can solve this and/or get a better idea of what needs to be done to solve this. Thanks for the input!