The 06 Ranger 4x4 can be towed if the Ford Neutral Towing kit is added. Before that I think the answer is no for all Ranger automatics. The Ford Towing Guide mentioned in the previous post will give you the details - see the topic on "Four-Wheel-Down Towing" for each model year.
It may be possible to modify a Ranger for towing with a drive line disconnect or transmission lube pump. Contact Remco Towing to find out if they have something available.
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL