The 804A driver was the result of the same severe cost cutting at Altec that reduced the 604D Duplex to the small magnet 605A. Altec later capitulated and reintroduced the large magnet Duplex as the 604E, and upgraded the 804A to the 806A by increasing the size of the magnet. This difference in magnet size is not represented by the literature of the time, but disassembly of the drivers tells the tale. We discussed this subject a couple of years ago in a thread on Lansing Heritage:

60's Altec info