The 98 Geo Tracker is a different drive train than the 99, so the 99+ info does not apply. However, Remco Towing charts show that the 93-98 Geo Tracker 4WD automatic is also towable as is. I would be cautious about the manual front wheel hubs, though. As I recall, a friend who had the 2-door Tracker Sport had to make sure the manual hubs on the front wheels were disengaged (which they normally are except when in 4WD mode). Not a big deal, just something to check before towing.
You can review the 1998 Geo Tracker towing info here:
Application Charts | Remco Towing
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL