Here is a method that was posted back in 2013.

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"Peter Berard" <berard_m@...>07/08/13   #27940

   Tony,
   I use a method my dad taught me in the 40s, when flat windshields were the norm.
  First, get son tough spall string, I got the nylon kind typically used to snap a chock line.
put the rubber over the windshield glass and place the string in the dish washing soap lubricated outside grove. Slide the rubber onto the bottom body flange and force it tight to the outside flange. with someone holding the glass tightly outward to the outside flange. Pull the string from inside the car gently while shoehorning a bit with a bent screwdriver. Work slowly, and you might have to try this several times till ya get the hang of it.

  Now, I found the present day rubbers to be quite fat so a lot of coursing will be needed.

   Of course the size of the glass is critical, but I had mine cut using the old glass for a pattern, so I have to blame the rubbers. I'd have made  the glass a eighth inch smaller in width and height if I'd known this, but I still got em in.
  Hope this helps...............p
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I have not tried it, so use at your own risk.

Jim...

> On Apr 5, 2019, at 4:42 PM, Sandy Smith via Groups.Io <tarmaciron=yahoo.com@groups.io> wrote:
>
> Can anyone provide instruction, tips or tricks on installing windshield glass in a 51 CD.
> Fighting with this ! Without success
> Thanks
>
> Sandy Smith
>
>
>