Okay, that's different from what I call "lock seal." The inoperable plexi
windows that come in the front and rear of the Bolers and many Scamps have a thick black rubber gasket around the outside that has a little trough in it. The way it works is that you install this gasket and the window, and then you put a "lock strip," which is a smaller rubber strip, into the aforementioned trough. This spreads the larger gasket and "locks" it in place. This gasket goes directly from the
fiberglass to the plexi of the window.
I can't see your window, but if it were me I would see about saving it rather than going to the fixed window. Many of those grey strips were bought from common suppliers and are still available today.
www.vintagetrailersupply.com is one source, and there are others mentioned in various threads here. But vintage's photos should give you an idea.
It sounds like you should first of all remove your window and clean up the trailer opening. You'll have to do that no matter what. Then you can take a look at your window (when it's out), and see if it might be worth rebuilding and saving. If you do save it and re-use it, I would put a rock gaurd (lifting panel of fiberglass) over the front to protect it and provide some relief from gross rain while you're going 60 mph.
For the best input from us, you're going to have to break down and figure out how to get photos posted here. I did respond to you some time back when you asked about how to do this in a photo thread -- if you could take a look at that thread and get back to us we might be able to point you in the right direction for that.
Right now we're all kind of shooting in the dark, with no visuals and only a short description. Picture = 1,000 words
Raya