1993 suburban 4 wheel drive

[peter]

I have a 1993 chevy suburban just today backing out of driveway I hear a loud noise and boom 4wd shifter is in netural. Put it back in 2wd very easy and drove away just fine. Then when I got home backing into driveway same thing again. I checked the u-joints them seem ok. I'm going to check motor and trans mounts, but have not yet. What should I check for?

[booondocker]

NOT good...transfer case...get ready for some real work and expensive repair.