3/4 and 1-ton trucks use a special snap or clip ring.

Cars and Corvette have a similar flat retainer GM 472521, but I believe they have a smaller diameter rear axle. Here is the Corvette forum on this subject (https://www.corvetteforum.com/forums/c1-and-c2-corvettes/4429138-1954-rear-end-questions.html). Can't find them. Different idea on purpose.

I looked at a 1961 Master Parts List Trucks for GM 370251 and it said 1938-42 Comm., 1946-59 1/2 ton (exc. P/Trac.) and 1960-62 Ser.10. This many years and no reproductions and no used ones on the typical auction sites?

Could the cone-shaped retainer be originally flat and has become cone-shaped by using a bearing removal tool?

"Adding CFM to a truck will only help at engine speeds you don't want to use."
"I found there was nothing to gain beyond 400 CFM."