700r4 transmission kicks out of gear on 85 blaze

I need some help in finding out a problem of mine. I have a 85 blazer full size with a 454 engine, and a 700r4 od transmission. I recently recieved the blazer from an uncle who passed away. The transmission was running fine until recently, when i was driving down the road and the gear kicked out. I pulled over and tried to put it in park but it made a winding noise and would not set into any gears (p,r,n,d,od,2 or 1). I got off made sure everything looked alright on the tranny, which it did. Checked the tranny fluid which was good. I got back in threw it in 4 wheel and it went. Funny? So i threw it back into 2 wheel and it worked. So i drove it a little ways and the same thing happend all over again, and again all the way home. Im not sure if its the tranny or the drive shafts or maybe the transfer case. Any help would be much appreciated so when i got to a mechanic i can have a better idea of what im looking at.

Sounds like the transfer case has a problem.

Check the transfer case fluid lately?

yep, sounds like the transfer case is popping out of gear. Take a look at the linkage to see if it is bent or binding up.