lowered pinion angle help....

[merlin65]

hey everybody, my truck (shortbed 3 speed sagi, 3:73 12bolt posi) is lowered 6inch springs, 2" blocks in rear and cut springs in front. For a grand total of 8" in rear and 7 in front. well she rides great and have always been satisfied. But the truck always had driveline vibration at around 70 under some throttle (short bursts of hell yea on interstate). Never bothered me too much since I dont travel over about 62 mph. But tried to fix it with some 4 degree shims from Carls Speedshop. Put them in with fat side toward front to kick my pinion yoke up to match my transmission. Drove it and now the vibration is at 35mph. I can feel it when I run out second gear before hittin third. It is also there at the bottom of third. So it seems it is not engine fan or anything like that. Brand new tires, new balance, but did it with old tires before I changed them and u joints are good. Blah Blah. It seems like pinion to me.
I was rappin to some guys and they said to try to reverse the pinion angle to be pinion yoke down. I agreed what the heck, gotta take them out anyways might as well spin them around to be fat side toward rear of truck. Do you guys think this might work? Before adding any shims the pinion was level pretty much with ground, kinda a 0 degree condition. did great except for high speed runs. Any help is appreciated. Someone has to have messed with this problem. thanks guys