OK need to pick your brains for possible problems with my NP231 Transfer Case.

Today I drove about 70k's at fwy speed then along a 80k/h rd for 5 mins, got a red traffic light, as I slowed to a stop I felt and heard a loud clunk sound. As I went to take off in 2H I has no drive, so slipped her into 4H and got thru the intersection and heard a clunk clunk clunk sound and pulled over. Had a look under, no obvious damage. Checked 2H again and no go, so 4H to meetup point for an SJC run. Once I'd met up with Steve and Wolfe, tried rocking it back and forwards in differenent ranges. 4H and 4L work but only front wheel drive, 2H just spins exactly like it is in Neutral.

Managed to get her home in front wheel drive, occassionally getting clunk clunk sounds as gears align/un align in the t/case.

Any ideas on what the problem is in my t/case anyone had a similar prob??