Transfer case popping into neutral
 

Last week while loaded up [9,500lb trailer load] transfer case popped into neutral when downshifting in tow/haul mode when brakes were applied at top of grade. Thought I accidentally moved shifter too far when going from 4hi to 2hi an hour earlier. Today, unloaded, it did it again when in tow haul mode when downshifting on a grade. I used the tow/haul so I didn't have to use brakes on the grade. Haven't used 4hi for 40-50 miles.

So what is wrong? Linkage adjustment, worn parts or ? Thanks for the help.

Worn parts in the Case most likely! But check your linkage and mounts too!

The linkage moves just fine with no play so I guess the case is next. Went under truck to verify. Nothing bent or damaged. I have a real smart mechanic but for my FYI what would typically be the culprit?

shift forks most likely then bearings