I NEED HELP!
2008 Suburban LT with 2wd/4wd. Right front output shaft that connects the differential to the CV axle keeps popping out away from the housing. It only pops out about an inch, but enough to where it no longer makes mechanical contact with the sleeve that actuates 4wd.

So far I've replaced the snap-ring twice, and most recently the trust washer that fits between the snap-ring and the casing. At the same time I replaced the output-shaft itself with an OEM replacement. It would SEEM as if something is pulling on the shaft itself and causing it to pull past the thrust washer.
I replaced the CV Axle just to be sure it wasn't too short. The Front end is 100% factory (no lift, no changes to alignment).
EVERY TIME it pops out, it happens in 4wd. This is for a friend, so I am not with the person each time this happens. COULD turning on dry ground cause enough bind in the front end to create "outward" pressure to push the out-put shaft away from the actuator sleeve?
Any one else experienced something similar? I'm really at a loss on this... I've effectively replaced everything related to this..... I'm a A.*.E. Master Tech and have had these front ends apart many times without a problem...
Thoughts??
Thanks!
Kip

Thought Update: Small end of Output shaft rides inside of splined intermediate shaft that attaches to diff. gears when everything is fulled assembled.... Theoretically, if the intermediate shaft received pressure from in the diff that in return put pressure on the output shaft.... could it potentially cause the output shaft to pop past the trust washer?
.... Hmm.....