Concert Bass dating

[Babs]

How do you determine the date of a Concert Bass head? I looked it over and can't see and obvious date. There is a rather hefty little plate riveted to the back with a serial number (don't you love Sunn stuff!). I assume that would be the key. Does anyone know of a source that can map these numbers to years of manufacture?

[TnKidd]

Babs,
Im an appliance technician, not an amp tech, so these other folks in here know more than I do & can correct me if I'm wrong. Inside the chassis of most Sunn Amps, there is a sticker. (usually small & round) On this sticker there is a handwritten date. I've always assumed that this is the date the unit was built; but you know what they say about assuming.

[Anonymous]

Thanks for the suggestion. The inspection sticker is 6/18/73!