Altec 755As: Trying to make sense of age / EIA numbers

[algoriddim]

I've got some Altec 755As that have the number 501239 stamped around the rim. 501 is not a prefix I can find anywhere in listings of EIA manufacturing codes. Usually it is 391 for Altec. They have the 3 welds rather than the six welds that the WE 755As had, so they're probably made in the 50s. Any idea how to make sense of that number?

[algoriddim]

I did find some other KS spec 755As with "502588" stamped on them, that have the same encircled "S14" stamp on them that my pair has.

Perhaps mine were manufactured in September 1962? (3 digit EIA manufacturer code [501] + last digit of year [2] + two digit week of that year [39]) By 1963, the Altec catalogs are listing 755Cs.

http://streetcomanches.zohosites.com...ng-ramble.html

[tomt]

I've got some Altec 755As that have the number 501239 stamped around the rim.
501 is not a prefix I can find anywhere in listings of EIA manufacturing codes.

[Horn Fanatic]

I've got some Altec 755As that have the number 501239 stamped around the rim. 501 is not a prefix I can find anywhere in listings of EIA manufacturing codes. Usually it is 391 for Altec. They have the 3 welds rather than the six welds that the WE 755As had, so they're probably made in the 50s. Any idea how to make sense of that number?

I found an ALTEC 602B with the number 500769 stamped in the appropriate place, with the 20750 cone kit. No 391 number in sight. I also have another 602B loaded in an 833 Verde with the same cone kit, but without any numbers stamped anywhere on the basket or under the bell. No 319 something much less a 500 something. I know for a fact it's the original speaker, and it's not a re-cone. I can't say that I've ever seen an ALTEC without some sort of number stamped on the back of the mounting flange. As a former ALTEC employee I'm left scratching my head.

H.F.