first off....capacity...lesson one.....the first roto-swirls were 12lbs.....then the updated rotoswirls, with vanes sticking out all the way to the top makes it a 14lbs....the straight vanes, in about 3 varieties, makes this one a 16lbs, not to mention the wide cap, plus all three using the smaller filter pan....dictates these are the standard capacity in any form......
for it to be an 18lbs machine....the agitator would be 4 straight vanes, all the way up, and maybe 4 smaller ones near the bottom, a small cap with the super filter flo pan, which almost covers the whole opening, at this point of time should also have been turquoise.....white came along later.....
confusion comes when they went strickly roto swirl on both capacities, all white, small cap molded in, and 2 sizes of pans available....somewhere near the end of the 70's until they were discontinued.....
I may be a little off on this, but that machine is definately standard capacity......