Transmission issues?
 

I recently bought a 91 dakota 5.2L 4x4 that had been sitting for about 6 years. I topped off transmission fluid, took it in the woods and did a little climbing in 4 low. I went to enter back into 4 low while in neutral and it kept grinding like the transmission wasn't in neutral. Played with it for a little while and got it back into 4 low. A few hours later driving down the road at around 3000 rpms my truck starts like skipping my rpms will jump up and down erratically. A short while later I had to be pushed across a jug handle by a cop because my trans would not engage in any gears. Checked trans fluid and it was completely empty. Put fluid in to get it home and it didnt even make it 5 miles before really hesitating and than not enaging. As I was pulling to side of the road it sounded as if my trans was grinding(Park and neutral). You can hear the grinding real bad after I shut off off engine for a couple seconds, but while driving it goes away. Now for the leak as far as I can see its dripping off of the trans cooler lines but the exhaust gets in the way and I cant see where its coming from if its the line or somewhere else? This is my first 4x4 truck and just teaching myself how to work on them.

Possibly the transfercase shifter needs adjustment. Possibly by running the transmission dry you did some damage. As far as the leak possibly the oil pan gasket or the O-Ring on the dipstick tube.