I'll leave it to you to figure out what's changed over the last 70 years, here's from 2003: "This standard is the outgrowth of and supersedes previous editions that were published as B1-1924, B1.1-1935, B1.1-1949, B1.1-1960, B1.1-1974, B1.1-1982 and B1.1-1989."
http://www.ring-plug-thread-gages.com/ti-spec-ANSI-ASME-B1.1-2003-Changes.htm

Bill



Moved over to the Passing Lane

"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir
"When we tug a single thing on an old truck, we find it falls off" ~ me
Some TF series details & TF heater pics