Thanks for the tips - keep them coming please!
Yesterday evening, I ran into quite the puzzle of an issue. Tonight, I remained stumped for quite a while but I think I figured out what the problem is. So... I installed the driver side window glass last night. Like @jfa.series1, I could not put the window in without taking the frame out. No big deal, as I just put that in, so easy to take out. I put the window in and then the front guide, then the regulator, then the rear guide. Immediately, I ran into problems with getting the window to move up and down without excessive force. Things were not happy.
I fiddled with adjusting the front and rear guides for quite a while. Nothing was helping. And with the window at full up, one of the wheels for the regulator was coming out of the track. I quit for the night, but kept thinking about the wheel coming out of the track at full up position, and the difficulty. I also found this in the archive, and read it before I went to bed.
Today, I went to work pulling everything back out of the door. I had thoughts that perhaps the front guide was bent or worn, and perhaps some part or parts of my window are from a later car. The article gave me that idea.
I should have just checked the window first, because that is looking like my issue, but I messed around with comparing guides and regulators from both sides of the car for quite a while first.
Here are the etchings on the glass for the left and right sides respectively:
Given this thread from @kats
I think my left side door window assembly is from 9/1975. I am not quite sure how to read the one for the right side door window, but I believe it is indicating 4/1971 for my 6/71 car.
Taking some measurements, there are clearly differences in the metal stampings that hold the glass and that the regulator works in conjunction with. So, for now, I am calling the replacement door window my problem.
So, do I need to source another window, or just another window support structure? I will see what I can find.
A few more pics of other progress:
By the way, the factory door sill threshold screws are aluminum. Middle pic shows the slight difference between the original sill plates and the reproduction ones. The reproduction one is on the bottom below two new original ones. The "DATSUN" is not as pronounced.