All this window talk gave me inspiration yesterday to pop out my glass that I've been meaning to do for awhile now. Time to weld up some holes. I noticed that the Canadians didn't get the same memo about changing the glass codes from the story Bob posted. All of my windows have the same bug marked 5-52. The windshield says SP at the top, where all of the other glass has an SS marking. And they all have a big M underneath. I would presume that is for Mercury, but if they built Fords and Mercurys on the same assembly line together, I wouldn't think they would put forth the effort to use different windows. I suppose that's another of those little details for which the answer is lost to time.
Oh, and no window retaining tabs on my truck, ever. Look Ma, no rust!