Did you ever make any more progress on this, 68Polara? I'm in the same exact situation with my 69 Coronet wagon... the window won't go down, so I can't get the gate to go down. I haven't checked the fuses yet (I know, should have been the first step), but I am trying to explore my options as to what the issue is.
I never actually found anything wrong with the wiring on the polara. I never even found the fuse or circuit breaker that controlled the rear window, still a mystery. It was dirty contacts in the switches and rusty moving part in the gear mechanism. Taking everything apart and cleaning it fixed the problem. You should be able to remove the cover panel on the tail gate and reach up in there to where the motor is. Find the rubber coupler that connects the motor to the gear mechanism and spin it by hand. You should be able to lower the window and open the tail gate. You can trouble shoot from there.
Hmm, I'll try that, then. I'm just hoping I don't have to break any of the panels to get into the mechanism. The trim around the gate handle is already a little bit messed up and pieces of it are cracked off. Thanks!
Power window Sometime back I found something on eBay called a " regulator gear" It was a little white round plastic gear that fixes the power windows...... I guess if you havent fixed it yet and havent checked ebay yet I would try that.