That IS the
standard breather (48-6766B), as found on the 12 cab. You couldn't use a bayonet style Oil bath cleaner because of the angle it's tilted at, the oil inside would not sit level. The Swan neck pipe I pictured above was actually removed from a 12 cab truck, and had me baffled until
Chris Vickery was able to provide me with the filter. I had previously picked up a bayonet Oil Bath filter, which came off a 13 cab truck.
The Service Bulletin amendment came out in 1941 and was not just specific to CMP trucks, but covered all Ford V8 vehicles in dusty conditions. It is of note to record that although the United Oil Bath air cleaner is made in the USA, the Service Bulletin and part numbers indicate that this is a Canadian modification (presumably following Commonwealth experiences in North Africa) and I have not seen any US manuals showing the fitment of the Oil Bath filter to US cars or trucks.