Killing carrier bearings

My truck keeps killing center support bearings and I can not find the cause. Toyota doesn't know and it's not like they are cheap. I never had this issue until after I was lifted.

The lift I had has 5100 @ ZERO with allpro standard leafs. 2 OEM units went bad from July-September 2013. Removed my lift and installed all OEM shocks, struts, leaf packs and had an alignment. Truck has no vibes and drives fine but every 1000-1500 miles a carrier bearing is COOKED. Since November 2013 I have replaced 4 bearings and the entire drive shaft which snapped in half at the carrier bearing.

Why do they keep going bad? I replaced the entire drive shaft with one out of a 1997 and that one went bad today...What is going on?

Recent work
Solid Engine and Transmission mounts
drive shaft
rear end straight
drive shaft balanced

 

All I can think of, is over-lubing the drive shaft at the "spline zerk" near the rear-most u-joint.

 

Is your driveshaft able to plunge or slip in and out with changes to the suspension ?
Sounds like forces are being applied to the carrier bearing with suspension travel .
There may be room for the slip and stub to move while the truck is relaxed but have you accounted for weight in the box and suspension travel ?
If i had to guess , the slip and stub doesnt have enough travel
Have you cancelled your drive line angles ?

 

Is the driveshaft properly phased? http://www.4crawler.com/4x4/CheapTricks/Driveline-101.shtml#Phasing

Why do they keep going bad? I replaced the entire drive shaft with one out of a 1997 and that one went bad today...What is going on?