Sometime back I picked up a circa '71/'72 215-S, the companion cab to the Concert Bass head with the narrow side port. It's in fair shape, loaded with a pair of 15" 'Sunn Transducers', essentially stamp frame square magnet Emi's(67-7309 code)with chrome dust caps. Anything special about these drivers, or are they, as I suspect, just run of the mill OEM stock speakers? Marginally better than the CTS's that came in the Sorado cab, right? I've got a pair of Altec 421-A's, and think the 215 would be better served with those, as long as the narrow slot ports load down the enclosure air volume properly(yeah, I know about the Altec cone excursion discussion). Any thoughts? Is there any demand for these transducers? I myself am not that much of a 'historically correct' parts person, except for keeping JBL D-140's in 200s cabs if possible.