I had a heck of a time figuring out how to put the windows into my 55 2door post
Unfortunately there where multiple parts missing and the welded on triangular pieces had fallen off the bottom of the stell window channels
I contacted a couple of the local window shops that deals with old cars and luckily the place where I bought the window glass from Georgia Classic Chevy Parts - (770) 921-3244 where awesome to deal with.
Steve helped me through the whole project before I even new about Chevytalk.org and trifive.com which he told me about
here is part of what he wrote that really helped me
Hi Mike. Originally, the glass was set in that rubber with the flaps. Forget about using the rubber with the flaps. Too hard to deal with. So use the glass setting tape I told you about instead.
Those rusted "tracks" are actually called glass setting channels. The tracks are the things the rollers ride in.
The 6" track that is attached to the bottom of the glass setting channel is supposed to be where the roller from the window windup regular arm rides in.
On each end of the glass setting channel there is supposed to be a roller attached to the bottom. Each roller is on a little triangular piece of metal that is welded to each end of the glass setting channel. One rides in a long track in the front and the other in a short curved track in the back. Both of those tracks should be fastened to the car with a couple of nuts and a few large head screws. The rear track you mentioned that you said is welded, sounds like one of them, but it should not be welded to the body.
So when you're ready to put the glass in, don't put the front and rear tracks in yet. Put some white lithium grease on the rollers. Put the glass in and get the windup arm roller in the track on the channel. Steady the glass with one hand, while rolling up the window until the window is all the way up. Then put the front track in, slipping it over the front roller and loosely screwing the track to the body. Then do the same with the rear track. Then snug up the screws and nuts. The nuts are on adjustable screws, which allow you to move the window in and out if needed. Roll the window up and down to check its operation.
Sorry, but I don't have a sedan here for pictures. If you get a 55 shop manual, there are some glass installation instructions in the body section. It isn't that good, but better than nothing and anybody with an old car should own a factory service manual for it, in this case called a 55 shop manual.
Something that I think would help you alot is to go to
Some tips I remember where that the first quarter window took me and my father about 4 hours
the second one took me by myself about 30 minutes
The local glass shop recomended to glue the windows in with a high grade black silicone which I did and worked out very nicely.:tu
I believe steve recomended setting the windows in the tracks about a 1/4" towards the front of the car to prevent them from coming out of the felt tracks as they are rolled down.
Also remember to put the trim on first I used 210 trim and a different than factory style and there where nuts that needed to be tightened that with the windows installed it would not allowed that.
Hope this info helps and if you need side glass Georgia Classic Chevy Parts - (770) 921-3244 where awesome to deal with