Can I safely tow my xj with all four tires down. It's an '89, 5 speed manual transmission. Can I put the transmission and transfer case in neutral and hook it up to a tow bar and pull it cross country? Any problems or concerns I should be aware of?
You should have no problem doing that, just make sure that your steering column is unlocked and you have good mounting points for your tow bar. You can find a good, cheap, tow bar for about $100 at Pep Boys.
This is how I towed a Toyota 4x4 longbed pickup 2500 miles from Phoenix, AZ to Guatemala. I also towed a Mitsubishi Montero from Phoenix to Wichita, KS when I move here the same way. Also make sure you have a good tow rig, on the trip to Guatemala I used a 85 Toyota 4x4 truck to tow the other one with and was not able to get over 55mph without things getting really scary. It made for a real long trip.