3/4" axle shims?
 

I have a better handle on a driveline noise problem. this could be helpful for many people. Based on the info from 4crawler
http://www.4crawler.com/4x4/CheapTri...FixingProblems

I checked the angle of the trans flange and the pinion flange there was an 8 degree difference in the flange angles, the pinion flange is recommended to be 1.5 degrees lower than the trans flange meaning I needed to move the pinion down 9.5 degrees.
I had some shims laying around that equaled 7/16" of taper so I installed them and it changed the angle by 5.5 degrees so I ran it down the road and it made little to no difference.
realizing that if I put the frame on stands and unshackled the rear of my springs I could put my floor jack under the diff housing and lift it to decrease the pinion angle while my wife was in the 4runner accelerating and decellerating the driveline. As a safety measure I put another set of stands under the axle housing to insure that the tires could not touch the shop floor.
well just as 4crawler said when the pinion angle got to 1.5 degrees less than the trans angle the driveline noise went away. Amazing!
Some quick math tells me that a shim with 3/4 " taper will give me the desired angle. seems like a lot of shim so I am thinking of cutting and rewelding the spring perches.
Has anyone done this much shim before?

Have made shims 1" thick and even thicker, 12 degrees and even more. By 3/4" taper, assuming that is over the 4.75" long perch, you are looking at about 9 degrees. I've run up to 8 degree shims in the past without issues (aside from needing enough extra u-bolt length).

If you have the ability to relocate the perches, that is the best option, but be sure and do a good job removing the old perches (don't cut through the axle tube) and a good job welding the perches back on in proper alignment.