Spirit,
Yours has a shop number or mold number on dome. There are many x's and number configurations. XO is common to see on these. Yours is referred to as smooth base. Never seen the breakdown you posted before.
Undoubtedly a Brookfield product. Like you found, many 121 types. Duquesne have 4 ribs on the lower wire groove. Pleated skirts are found here in Missouri to Kansas. There are so many AM. TEL. & TEL. variations. AT&T is the shortened version.
Yours has a shop number or mold number on dome. There are many x's and number configurations. XO is common to see on these. Yours is referred to as smooth base. Never seen the breakdown you posted before.
Undoubtedly a Brookfield product. Like you found, many 121 types. Duquesne have 4 ribs on the lower wire groove. Pleated skirts are found here in Missouri to Kansas. There are so many AM. TEL. & TEL. variations. AT&T is the shortened version.