Bob -
You are absolutely correct -- the plastic door handle and lint screen cover are perfect give-aways indeed.
I've discussed these with James/70-series a few times, and we have at least loosely concluded that Sears made the swap to the plastic door handle across the board in 1972. I don't think I have ever come across a 1972 or later production KM dryer that did not have the plastic door handle, even Lady K dryers. There were many new models for 1972 though, so that may be part of the reason for the fast turn around.
The lint screen cover I haven't thought much about, but before too long the hinged plastic design that we see here gave way to the screen with the all-in-one plastic handle that doubled as a cover, on most models.
Strangely the '72 door handle didn't last long either, as by later 1973 the flush door handle (which was used for more than 20 years totally unchanged) was introduced. The 1972 handle, with that awning-like overhang on it, seems to work well and feel ergonomically nice, but Sears seemed to drop it really fast, I'm curious as to the reason for that!
Now that I think about it, several things went to plastic in 1972-1973 in both KM washers and dryers --- the washer tub rings, the front feet on the washers, the lint screen covers, and the dryer door handles. They also eliminated the lid handles in the washers in 1972. They must have been on a cost cutting campaign!
By the way, Tom is right about the most BOL of Kenmore dryers - for a number of years they had the dial on the front of the cabinet and no console except a little piece of trim along the back. The last of those was offered as a 1976 model. It had a 4,400 watt element and was available in two versions, one with an internal lint screen and the other with the top mounted screen. I've seen one 1976 model like this on Craigslist, never seen one in person except in the stores.
Gordon[this post was last edited: 3/19/2014-22:31]