Tranny Or Transfer Case ? 2005 Seirra

[GregKg]

i was at stop sign pulled away than heard a snap than aloud grinding noise thought it was drive shafts but everything in place and truck dont move and wont go into park and when try to put it back into drive makes grinding sounds any ideas i just tried unhooking battery did nothing but in 4X4 it goes into park and makes no grinding noise but when i hit 2 wheel drive it comes out of park and rolls help please and thank you