Pretty sure that's a 610S, and those drivers are Sunn Transducers.
The cabs were available as a 610S with Sunn Transducer drivers or a 610M with Sunn Magna drivers.
Hartzell actually had a speaker manufacturing facility down in that far western "speaker" corner of Kentucky where CTS was, and Eminence and WGS still are, and they built (or at least assembled) their own proprietary drivers.
As with many industries in the days when the US manufactured pretty much > 95% of it's consumer goods, the components; motors, baskets, etc. were often shared 3rd party items rather than actually fabricated by the individual branded company. Not dissimilar to the way the RV builders share 3rd party components and are clustered in and around Elkhart, IN, auto manufacturers in and around Detroit, furniture manufacturers in the Carolinas, etc, etc, etc...
Even speaker EIA codes from that get garbled, CTS might have sold some stamped baskets, magnets, cones to Eminence or Sunn or vice versa when one of them needed to fill a large order and ran low on components.
For all intent and purposes the Sunn Transducer had an Eminence and/or CTS mass produced "clone" driver that can today be found be labelled as any of the manufacturers.
