the very first posting pic....and the picture I posted(the middle and right) use the SMALL filter pan......
for a 60's machine, most should have had a ramped agitator......
but later in the 60's into the 70's, a 3 straight vane was introduced as well....it was mostly about capacity, 14lb machine was normally a ramped(black), yet the same basket with a straight vane(blue) now became a 16 pound machine......it was a matter of the shape from the ramped coned shape that took up more capacity...
filter pans were usually white or blue......I lucked out getting a few dispensers that hold up to a cup of softener......although the Jet-Swirl units were unique as dispensing when the filter flo started, less chance of staining....
some of the larger filter pans also came with a deeper section in the middle to hold softener after the spin stopped, then added as agitation started.....
I believe the bigger basket was all about capacity, and the introduction of the Mini-Quick cycle......then turned SpotScrubber, only difference of those baskets was no holes in the bottom....but would still work on either machine....
without that top section, the filter pan kept the clothes inside during spin, the other ones could be used without the pan....
just a bunch of different designs and ideas they added along the way....some better than others.....