Take care when you loosen the nut that holds the outer gasket and wiper-arm on. I cracked the motor housing when I replaced my old one.
If your window is stuck in the "up" position, you can remove the wiper motor by working from inside the cargo area. (I did this myself during the winter.) Remove the carpet, then the access panel and you're there.
Plan on checking and fixing all of the following while you are in there: support rail holding the glass to the regulator arms; washers holding the regulator arms to the rail; side channels for the glass; inside and outside weatherstrips; outside lock/switch; wiring harness; defroster relay.
Matthew W. Woodruff<br />firstname.lastname@example.org<br />1989 Grand Wagoneer \"Laredo\"<br /><br />What works: tailgate window, rear wiper/washer, power windows, A/C, temp and compass, seat belt buzzer, fog lights, cruise control<br /><br />What doesn\'t: gas gauge, remote door locks, rear window defroster, cigar lighter