Those are modified Altec 604-8K's as used in the UREI 811-A, 813-A, and 815-A systems. I don't believe the modified 604-8G's of the original 811, 813, and 815 series ever incorporated the additional foam dampening material in and around the horn. And, of course, the 604-8G's are Alnico as opposed to Ferrite for the 604-8K's.
