front driveshaft vibes

hey all,

after re-gearing from 3.55s to 4.88s, there was a bad vibe in my front driveshaft. i pulled the driveshaft and it had a bad cv so i got a new driveshaft from a junkyard in excellent condition. the vibes are still there. they go away when the shaft is pulled. i never noticed the vibes before re-gearing so im assuming its related to d/s rpm.

searching came up with a few possible things to check:
CV socket/u joints on d/s
t case output yoke nut torque
pinion angle
output bearing

symptoms:
bad resonance and vibes above 70mph
whirring/chattering noise at 20-60mph, but no vibes
at idle speed it makes funky clunking noises but doesnt produce vibes.

things that are new:
front pinion bearing etc all replaced when re-geared.
driveshaft is in good condition and well greased
front pinion angle is good
u joints in front axle

checked:
tightness on front output yoke on t-case
u-joints in front d/s

Specs:
1990 xj
dana 30 HP
6" lift
np231/aw4

im leaning towards output bearing on the front of the t-case how can i test this and how is it replaced? i have rebuilt a np231 with new chain, oil pump, and modified one for a sye, so i know i can do it.

TIA
-Tim

vibes

I know it sounds good, but have you checked the fluids in your diffs, and transfercase. It sounds like the noises my transfercase went out because it had low fluid

i didnt mention that, but yeah it is full of good fluid.

-Tim