NOTE: A recent find prompted us to verify the table and we found two errors.
Reed Armour prepared this index of K and F series Crowfoot wrenches. As far as we know, no other full listing presently exists. Crowfoot wrenches received only sporadic mention in catalogs, therefore we believe the vast majority were produced for contract. The contractors name was not stamped on the tool, as was the normal procedure. This may be attributed to the demand for Crowfoot wrenches by many small companies, particularly the Aviation industry, where they were used extensively.
How companies learned about crowfoot production is a bit of a mystery, but probably included word of mouth, company representatives, or advertisements offering to manufacture specialty wrenches.
Dale More, of California Tools, assisted by completing a catalog search. Dale included the following information: "The crowfoot wrenches first came out in 1/2" drive in 1929. The original series were DC-8 through DC-12, later these became 5712-5724. I assume they're rare since I've never seen one. These are in the early 1930's catalogs but were gone in the 1939 catalog. They came back in a 1939 supplement and then in the 1940 catalog as aviation crowfoot wrenches in 3/8" drive only, under the US-512 - US-572 part numbers. In 1942 these were gone and the 3/8 " drive series 4912-4944 appeared. I looked until Proto 1957 and didn't find any 1/2 " drive Crowfoot wrenches."