The rear window motors on a convertible have an extra gearbox on them, with plastic guts. I have broken two. The motor runs, but the window slips or sticks, or drops down, etc. Unfortunately, the fact that they are different makes them harder to come by than standard 5.0 front window motors. Even worse, I believe that they are specific lefties or righties, making it more complicated. You can use the motor itself from a standard front window motor and adapt it to the rear window gearset, but it's usually the gears that break, so that's little help. I scavanged mine from the junkyard, but I expect that source to start drying up, if it hasn't already. I think I paid $5 or so, but I assume that a dealer will rape you for the price.
Oh, and to get at it, you have to pull the plastic side panel (including the speaker and window switch) off. It's more or less routine disassembly/reassembly. The only tricks are that you need a Torx bit to get the seatbelt assembly out of the way, and the three (I think) small bolts holding the window motor to the window track assembly need some nimble fingers. No big deal.
