My 1986 rear slider and your 1985 slider windows
were Herr 4600 or 4700 models(old age eludes me witch one. Its marked on the frame if you remove the window) which were obsolete along time ago. I spent months looking for a replacement lower track. You will have to order new windows
if you need to replace those old radius slider windows
. Good thing though the new ones will have better seals and slide easier. You will need to check with Scamp to see if they stock the same cut out size. Remove the inside trim ring and measure the frame width and heigth. Please let us how it turns out.