I agree with the above. The metal handled PowerPath uprights Whispertone, etc were still being made in 1996 with the new logo, as I have a brochure from that year.
My parents bought a hunter green Kenmore Whispertone canister in later 1999. I do not remember if the Progressive canisters were out then, but I'm pretty sure they were. The Whispertone wasn't TOL anymore and was the more basic model, and later it changed from the squared body to a jellybean shape more like the Progressive around 2001.
And the early Progressive canisters didn't have Whisperbelt power nozzles it seems.
The yellow logo tended to appear on blue vacuums whereas the more gray one seemed to be on green colored vacuums.