Hi dbt,
The tech tips is new to me too. I have a way to deal with the windshield connecting bars that internally retain the two windshield halves together, (see link for illustrative purpose only)
http://www.oldchevytrucks.biz/34_46/full.asp?page=135Rather than welding and patching, I have been successful more than once, by drilling out the screws that will not budge, at this point, the three-hole brackets will be off as well. Then one side or the other will separate with light heat, lots and lots of soak time, (weeks) Kroll and/or PB Blaster and with light tapping on the outside of the frame, (wooden hammer) effectively pulling the two half’s apart. I have even busted out the glass into a 33 gallon trash can (Safety Glasses and Leather Gloves) to assist in the pulling, tugging, tapping for oil penetration etc.
Once you have successfully separated the two halves, invariably the windshield connecting bars will come out of either the drivers or passenger side of the frame, leaving one or both protruding. If protruding, you then have some meat to place it into a good vice, and have the ability to wiggle, pull, tap, light heat etc.
For the windshield connecting bars that will not budge, if protruding, cut it close to the center channel with either a hack saw or air cutter wheel, leaving about 1/8th of an inch exposed. (this is my secret) Some may have split right at the center point of the windshield channel. Whatever is exposed and left hanging out of the channel, use a fine file to de-bur any boogers and sharp edges. You may now use a undersized punch and drive the windshield connecting bars deeper into the channel. It was at this point that I decided it was either sink or swim. It has worked on many windshields that I have taken apart.
To determine the depth of your punching/driving of the old connecting bars, a new one that can be purchased aftermarket, and you may use it as your go/no gauge.
As an addendum, one half may be too rusty, split, buckled and have oversized weather-strip channel. But now, you only need one side, and may be able to find used or NOS.
After taking a few apart, I have been able to re-mate halves from two different parts trucks.
Hope this helps.
Dale