Hello Kevin
Interesting question!
I'm not John, but I have a lot of information to offer you.
First, it does seem like the Canadian Inglis machines were nearly all standard capacity. I did see some pictures of a late model large tub machine with the Penta-Vane, made I think several years after U.S. production ended. If I can dig it up I will post it or post a link for you.
Here is what I can tell you about U.S. machines: There are five distinct capacities / tub sizes, with a tweak to the standard capacity in 1981 that might change this to six.
First and smallest is portable tub that began production in the early 70s. I do not have a pic of one of these right now. This is the revised, fast spin portable that replaced the older portables which were near clones of 24-inch stationary models.
Next is the 24-inch cabinet machine that I just mentioned. Many people mistake these for standard capacity 29-inch tubs, but they are noticeably smaller in overall height and diameter.
Then comes the 29-inch standard capacity tub. These were in production from the 1950s to 1981. One of the 'Features at a Glance' stickers still on one of my machines states the tub capacity to be 2.36 cu ft. This is with a straight vane agitator. When a DA was used, this number may have increased.
Maybe next is the late 1981 and later standard tubs. I say maybe because their outer tubs are 3/4 of an inch wider, but I do not know if the basket was redesigned, I have never been curious enough to measure one, but I assume it was. This change came about when the switch was made to the 'energy efficient' belt drive in summer 1981. Dimensions, capacity and water usage were reduced slightly for the large capacity models, to make them compare better on energy guides. Large tub water capacity went from 26 gallons to 22. When this switch was made, the standard tub retained the same outer diameter as the new large, just with a reduced overall height. The older standard tubs have continuous rows of perfs at tub bottom, the newer have interrupted perfs just like in the large tubs, in fact I think the factory used the same stamping dies to punch the perfs in both sizes, which is why the large tubs have such a tall un-perfed region toward the top rim. I do not have a pic of one of these either, but there have been some good ones over the years here on AW.
Next up in size is the 1981 and newer large capacity that I mentioned above. 2.8 cu ft capacity was always quoted on these, with DA, Penta-Vane, or DoubleDuty Surg.
Finally, the largest is the 1967-1981 large capacity. This tub can be most easily called-out by the four rows of bottom perfs, that are clustered into three groups, followed by large areas with no perfs. Water capacity is up to 26 gallons, but later, some models were set to use only 25.something, probably to reduce published energy consumption. These are the largest belt-drives, and probably the largest machines available in their time. I have seen capacity quoted from 2.67, to 2.71, to 2.98 cu ft on these, so either measurement standards changed, or the capabilities of agitators was being considered along with tub dimensions even back then.
I took a bunch of pictures with my iPad today for you of machines that I have either installed now or in my garage. I hope these pics and info helps.
[this post was last edited: 9/2/2017-11:17]