Dodge: four wheel drive, dodge ram 2500, automatic transmission fluid

Question
dear ram man,
i have a 1996 dodge ram 2500 4x4 with a v10 motor with 84,000 miles.the four wheel drive worked yhis fall but now it doesn't.i engaged the four wheel drive,then jacked up the front passenger wheel.the wheel spined freely. then i checked the front driveshaft.it did not turn.i also looked at the vaccum shift motor and the vaccumm hoses were tight.i also changed the transfer case oil with mopar 7176 transmission oil,which is the correct oil.is there a fuse or fuse link for the 4x4,or what else do you suggest to do or look for and do? don't want to go to a repair shop unless i have to.
thank-you
mike  

Answer
Mike,
The transfer case lube is dexron 2 automatic transmission fluid.Mopar is fine.I would have the vacuum shift motor checked.It is obvious that the problem is from the front driveshaft to the wheel.If it just did it since this fall without you knowing,it can't be anything major.I would either have the vacuum switch checked or replace it.If you don't want to take it to a shop which i don't blame you,you'll just have to start troubleshooting.but this is where i would start.