2 piece driveshaft pinion angle... raise carrier?

[jks67ss396]

guys

Ive got a 5.3 4l60 in my 71. its my daily driver

I have the slightest vibration under throttle in the range of 1500-2000 rpm.

I believe its got something to do with the Vintage air setup I have. seems like if i pull the compressor and run a short/stock belt, the vibration goes away. put compressor and longer belt on, and i get vibration back.

But i want to rule out pinion angle once and for all...

Back when i was doing the swap, I checked pinion angle with this:

http://www2.dana.com/pdf/J3311-1-DSSP.pdf

and i wanted to post the numbers to see if they look ok to you guys.

originally, i was using a cheaper gravity angle finder and ordered shims accordingly. But ever since, ive been using that craftsman digital gauge which seems more repeatable.

for reference, my driveway is about 3 degrees downhill.. all following angles are absolute, so subtract 3 if you want reference to level, but here, its all relative angles so driveway angle doesnt matter...


my transmission angle (as measured on the rear seal surface): down 6.5 degrees (remember driveway i 3 down, so real angle is 3.5 down)

front driveshaft angle: down 7.9

rear end angle is 8.2-8.3 up

from the article, trans/front driveshaft working angle should be 1-1.5, right? and it is.

and from article, rearend should be same angle as front shaft, right? and its .3 -.4 out.

What do you think? am i ok? just not sure that .3 degrees is worth buying new shims, ubolts and nuts when im almost sure its the belt harmonics

thanks!