What breaks low side of DHD that still leaves hi side usable?

[Got Smoke?]

Went to a pull last night. Had an issue with transfer case coming out of low range at my last pull. Forgot to readjust the linkage so I just held it in place like I did last time. Well 5 ft outta the hole LOUD bang...grinding metal on metal as the rpm's came back down when I hit the clutch.

Hi side still works fine, 2wd still works fine....drove it on the trailer. Any clues, guesses before I pull the case out tomorrow night?:what:

 

[kino_fab]

Broken planetary? broken shift fork? who knows

 

[cahammer]

im going with the shift fork or bad bearings

 

[Cummins Driver]

Josh just had this happen to him. Low side died, and high side still worked.

I think he said a snap ring broke in there letting a gear slide back some to where it wasnt making full contact with the other gear. When it slid back, the half of the gear that was still making contact just stripped.

Eric