US 1968 2nd Pattern 2 Quart Collapsible Canteen and 1969 Cover 

I use these daily at my homestead and used them extensively when I was in the Army. The piling is great to soak and evaporatively cool the canteen. Makes a very noticable difference (especially in the heat of Iraq!) 2 quarts is a safe amount for my dog and I for a half a day or a couple miles of hiking if I am reasonably hydrated. Had a previous experience running out of water in the Utah desert, finding a cattle trough and gulping down the filthy stinking water 😂.. Love the video!!

That first version you mention in rubber is way more rare than "Rocking Horse Poo". When i was collecting Vietnam era US gear, i obtained several very early, several very late and several "XM" experimental pieces of equipment. But in over 8 years of collecting this gear, this item was one of the 2 that i never obtained. The other being the so called M67 Buttpack?...Its debatable still. 8 years and never found one of these. You are really lucky to have this item.

May I ask where you were able to get one of these pre-1972 covers? Ive been looking for one for a while without absurd prices.

The bottle spout on 72 version also seems to be at a different angle to the earlier one.