I've got a 71 Vista under restoration now. I'm sanding and prepping everything for paint. I want to get all the trim off the tailgate and the window and I'm struggling. I removed the glass from the tailgate, but now the door won't open.

I spent 45 minutes last night trying to get the gate unlatched. There's a safety mechanism that's keeping me from doing it. Please see the attached sketch.

I think the mechanism is mechanically actuated somehow. There aren't any wires running to it. The only wires go to the switch that I think keep the window from opening if the latch is open. Can anybody help?

 

It could be a few things but if it worked before you took out the window it sounds like the tailgate window blockout lever rod.

It's a rod with a right angle on the end goes down from the latch. The window pushes down on it in the full open position and if it doesn't the door latches are locked out so the gate can't be opened.
Pull down on that rod or lash it down somehow and try it.
If it isn't that it has to be something hanging up in the latch or the lock synchronization is off.
The Fisher Body manual has a tailgate section with adjustment procedures and diagnostics.
#11 in the pic.

 

That's got to be it! Man, I'd love to have that Fisher Body manual. I've got the engine and chassis manual, but some of the stuff in the body manual would be priceless. Thanks a lot, Bluevista!
-Kurt