We usually just called them "tab washers" or "tab locks"in the jet engine plant where I worked. Most times they were made to fit a specific application, due to materials needs. Try some on-line sources such as AIRCRAFT SPRUCE AND SPECIALITY, as well as others who cater to the home built aircraft people. Also do an internet search for AN and MS fastner suppliers. Incidentally, although others will disagree, AN stands for "aircaft, national" and MS means "military standard." Thats what I was taught anyway, but will yeild to another valid opinion.