90 pathfinder transmission problem

pathfinder has 215000 miles. went to car wash sat. to get salt off of it. when i got done washing it i put it in gear and went forward about six inches then it acted like i put it in neutral no matter what gear i was in. i looked under truck thinking maybe u-joint fell out but all was ok. so i put it back in gear and looked under truck again to see if drive shaft was turning and maybe i broke a rear end gear, but no such luck. pretty sure trans just took a poo. if any ideas let me know, but my question is should i take it and have it rebuilt or should i buy one for $1700?

I'd try changing the fluid first and taking off the trans pan to check for debris/contaminants. Sometimes a fluid change will breathe new life into an automatic. Sometimes it doesn't, though.