Ovals and Circles
David,
You are right! I went to my trusty Kirby Service Manual from June of 1972 and looked at pictures of parts and the Kirby logo in the circle was only used with the 562 and Sanitronic VII. The Kirby logo in the oval started with Sanitronic Dual 50.
Fred and I talked this evening on the phone about this and he and I both agreed that Kirby was probably trying to use up some old material so that probably accounts for the odd 80 bag with the closely spaced ovals.
Thanks for make that clear. I will probably keep the earlier tan bag on my 50 since I have a "correct" replacement. It does look very cool. When I use the older models, I always bojack them so I don't have to clean out the cloth bags. With two cats the only way to get them clean is to turn them inside out and then go over then with a power nozzle or rug rat.