yes, what Fumblin sez, the different models weren't numbered sequentially, just part of the general flow, it would have been the 2,212th truck of any model made in LA for that calender year, it might have been the only Cameo on a given day, and with something like 275,000 commercial vehicles built in '58 [don't know what percentage was produced at LA, but I'd think at least 30,000 or more], and the Cameo dropped mid year, I'd guess it was built at the end of 57, when 58 production first started, and likely before the beginning '58 .... the resto pak from GM might have more specific info from your VIN, tho' I don't think they did too well with records back then
Bill
and you may get some clues about the month built from date codes on original parts, like block casting, trans, rear end