Installing quarter glass - '70 Dart
A couple of tips, just from my own recent experience.
This might seem obvious, but don't install the glass pane onto the frame until all the rest of the assembly is inside and bolted into place.
The most frustrating part for me was that every time I'd get one roller/slide into place, another one would pop out. I finally figured out that if I totally removed that rear channel (it has a slight curve to it and bolts through from the inside of the car; also has adjustment nuts on both mounting bolts) it makes it much easier. It opens up more room to work, and it's one less thing to pop out while you're working with other stuff. After everything else is in place, it's a simple matter to go in through the hole in the body panel and install it. You'll be able to insert the rear roller into that channel, slide it up into position and insert the mounting bolts into the body panel. The day I figured that out was a triumphant day!