Is it possible to:

[SunSoaked]

install the rear window glass backwards?
I have tremendous and annoying reflections in my rear view mirror. A new windshield, mirror and rear window tint has not helped. When I look in the mirror I see refections of everything in front of me. The dash, hood, road and any car that's in front of me.
Tonight, I was looking at the rear glass and noticed the label (or whatever you call it) that shows it's "Softray" glass, so I assume it may be original GM.
Sooo, it looks like the glass is flat? Is it possible to install the glass backwards and maybe this has something to do with the glare on the inside? The label is on the passenger side, lower corner and is readable from the inside. If the glass was reversed it would be on the driver's side and readable from the outside which makes more sense to me.

[Dead Parrot]

Look up Infinity Mirror. The vertical and flat rear glass works with the near vertical front glass and mirror to make one one. Made even worse if your eyes are near level with the rear view mirror.

Had the same thing going on in my 75. Got better when the mirror fell off the front glass and I replaced it with one that mounts off the cab roof. Changed the angles enough to decrease the bounce effect.

[Warrens69GMC]

Correct me if i'm wrong, but its 1/8" tempered, non-laminated flat glass.

Your local window tint place should have a mirror style tint to reduce "bounce back" and to help with headlights. And it will be DOT legal.

[Pontiac1976]

The rear glass or vent glass can be put in one way or the other, but the glass should have glass info label on the and should be readable from the out side. The label is faint white on the glass. or could be black if replaced with aftermarket.
The print could be on the inside or the out side. The year and plant it came from would depends. But readable from the out side if they did not put it in the wrong way.