Strange rear window haze wont come off easily

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The rear window on my 71 has a tough haze on the outside. I had the window out to reseal it and tint it so I was able, after a long time and hard labor, to clean up the edges of the glass for the new seal. I used fine steel wool and various liquids including window cleaner, WD40, etc. I left the rest of the window alone for now because I got tired of it and needed the window in. Now the window is in and the edges are haze-free. Does anybody have any less labor-intensive ideas on how to get rid of this haze? It seems friction or chemicals will remove it. Maybe like a buffer machine? The truck had a bed topper on it when I got it and so I think the rear window was left alone for many many years.