I'm sharing it with you because it's a surprise. This is a Rola Heppener of indeterminate vintage, originally fitted in a Hammond organ. 16 ohm, supposedly 15 watt Alnico. It sounds like a worn in Blue.
It's bright in a crystalline way but also very deep when you hit low notes. An organ's range is greater than a guitar and this speaker handles guitar effortlessly.
It breaks up like an AC15 and doesn't particularly like mid heavy overdrive. But it's delicate and sparkly and once you dial out the excess brightness just exquisite for fingerpicky stuff. My Strat has never sounded better.
Sorry for the rave but don't ignore old organ speakers if you come across them.