I have a 1970 C-Body Polara. The windshield had been taken out by previous owner, then set back in place haphazardly. I took it out and have done some rust repair and paint, now I need to reinstall. Have no idea how it was set up originally, like what type of rubber spacers do I use, what type of sealer (urethane?) and how to install. Found the trim clip kit on ebay. Cannot find any tech articles or other threads about windshield install on this year range of C body (69-73).

Windshield or Backglass?? Your post does not clarify...

Go find an OLDER auto glass shop in your area.. If you can find a grey hair working there he should be able to help you with what you need and advice....

Is it a Rubber-Type Seal, or a Ribbon-Type Seal? You can carefully pry up the stainless trim to check, or (better) someone here should know which type you have on a '70 Polara.

Ribbon Seals are a Tar-Like, soft, malleable substance, that uses Rubber Blocks at the bottom edge of the channel to position the glass in the opening. It is essentially glueing the glass into the channel, then stainless steel trim is used to hide the seal from view.

You can buy Ribbon Seal Kits at many/most local Autoparts Stores, usually near the gasket adhesives and sealants section. It is a fairly generic item, sold in a cardboard box, wound in a coil.

If you have Rubber-Type Seals, those are another matter altogether. You would likely need to order those and they are vehicle-specific.

it's the rear window, and it's already out. cant tell what was used before to seal, looks like a rubber sealer. I checked with some c body guys they say it only takes butyl rubber ribbon sealer, thats it. What I dont know is if I should get a tape that's thicker than the actual gap it needs to fill, because it may compress with weight and heat?

You don't need to completely fill the channel with Ribbon Seal. To some extent, you can press and form the ribbon material to conform to the glass and channel.

The seal material doesn't just remain as a square-corner ribbon. Heat, over time, allows it to melt a bit and conform to the channel as well.

The link below includes the Instructions for 3M "Windo-Weld" Butyl Rubber Ribbon. 3m recommends applying the ribbon to the cleaned and prep'd Pinch-Weld (channel):

http://multimedia.3m.com/mws/media/556441O/3m-windo-weld-sealer-bulk-08620-21-22-25.pdf

DC

Would contacting Steele Rubber products help??? They sell rubber window gaskets for everything under the "Sun".....I need to order the back window along with the windshield gasket for my 70 Duster....

You are confusing a gasket set with a glue in set...

NEVER used the square ( I did auto glass for a living in the late 70's into the early 80's)
We always used the round setting kit.. rule of thumb was 3/8" for the windshield and 5/16 for everything else...