Here is a good link to a photo step by step on replacement/installation.
https://blog.drivenrestorations.com/2016/03/1968-1970-b-body-mopar-windshield.html
Ive done about a dozen or so install on various cars. If you take your time and second set of hands you should be good.
I just did the Charger. It goes in the same way.
Except the factory manual said to start at the top, which didn't make sense.
Start at the bottom. I should have known better.
I started at the top and it was a screw up. Wound up fighting the bottom against gravity.
That link doesn't say. They may have used polyurethane that sets up in the lower channel.
I did not see it.
I though about it.
But if I did that, the windshield gasket would be in there for good.
Maybe not a bad thing.
I have put A body gaskets in with it all the way around.
It's nice because I have been able to change a windshield without the gasket moving.
But on the Charger I was worried about what if I had to take the thing back out.
So I used gobs of 3M 8509.
No way I would reuse a 30 year old gasket for this.
They shrink up after you take them out and they sit around a while.
They need to be pliable too.