This is according to the '92 owner's manual (slight paraphrasing):
Front lifted:
-max speed 35 MPH
-max distance 50 miles
-transmission in Neutral
-transfer case with 4X4 in the off or neutral position
-manual locking hubs in the free position
*IF the speed is going to be over 35 MPH, the towed distance is greater than 50 miles, or if driveline/drivetrain problems are suspected, removal of the rear driveshaft is required otherwise damage to the transmission and transfer case may occur.
Rear lifted:
-max speed 55 MPH
-max distance 50 miles
-transmission in Neutral
-transfer case with 4X4 in the off or neutral position
-manual locking hubs in the free position
-steering wheel locked into straight-ahead position
Flat:
-max speed 35 MPH
-max distance 50 miles
-transmission in Neutral
-transfer case with 4X4 in the off or neutral position
-manual locking hubs in the free position
*IF the speed is going to be over 35 MPH, the towed distance is greater than 50 miles, or if driveline/drivetrain problems are suspected, removal of the rear driveshaft is required otherwise damage to the transmission and transfer case may occur. With the rear driveshaft removed, the vehicle may be towed unlimited distances, while the maximum speed of 55 MPH must not be exceeded.
The '91 owner's manual states the same thing. I'm not sure about the second gen Explorers, but it seems this holds true for all of the first gen ones.
