Speakers do have a manufacturer code and are frequently date stamped.You will have to look at the driver frame- usually on the metal basket of the woofer (not the numbers on the paper cone) Look for a six digit number. Electro -voice is 649( the first three digits are the manufacturer code) the 4th digit is the year of manufacture- the decade is not provided, and the last two are the week of the year they were made. So if you look on the woofer from a Pair of EV Sentry 100a, from the 1st week of May, 1983, the six digit number would read: 649317. The first week of may would be the 17th week of the year. The 3 indicates the date of manufacture to be 1983 (sure it could mean 1953, 1963, 1973 etc- but an educated guess will get us past that).