The "vintage," older Zildian, like the '70s and earlier didn't have different lines like they do now. They were all just Avedis Zildjians or K. Zlidjians. Avedis and K. Zildjian were two separate companies back then.How can you tell which line vintage zildjians are? They are usually not inked stamped like they are now. How can I tell a K from an A..etc?