From what I have determined so far in my great amount of research into this, KLF seems to be correct. It has to be an SR5 to have power windows at all and I'm thinking that the production range is one of the differences. The catalog is not exactly crystal clear on the descriptions and usages however... They are all listed for the same model codes, SR5, production ranges vary.
jynx, as we discussed earlier, the switch you have in the picture above (a) I believe is part #84820-89104 which IS available, not disco'd, (sent one to someone else, also was wrong) and seems to have been snuck in all the way from 85 (only in Turbo trucks? Maybe?) and then used on some of the later production trucks, depending on what type of door panel you have. The one you received, 84820-89103-23, is if you have the other type of door panel (like busmup) and production range, again, varies.
The one that jynx has, is the LAST one they had in stock. It is disco'd and will no longer be available from this point forward.
I have sent out return packing slips and labels to those of you who bought switches and they were wrong. Again, I apologize for the inconvienence and I'm going to send you all a little something for your trouble.