1992 Pathfinder transmission problems

[92pathfinderguy]

Hi folks, I just googled up and found this great community, hopefully you guys can help me, I recently picked up a 1992 nissan pathfinder, 4wd auto, fully loaded, 180k on the odo, very clean truck considering its age and miles. well, I had a friend drive down, bought it and I drove it back, once I got up to interstate speeds after about 30 min, it kicked out of overdrive, and wouldn't go back in. about an hour after that (200 mile trip) the A/T transmission temp light came on, I slowed down and eventually the light went off. I was in the middle of nowhere so I didn't want to stop and get stranded. once I get to a small town I check the transmission fluid and its full. I try to go into reverse but it won't engage, drive engages but it won't shift out of 3rd gear. I tried chaning the selections on the transfer case but that didn't change anything either....