Well, he can debate it all he wants but they never made his speakers in ceramic. His was the Alnico series. This was according to his brother Kelly from like 1993. The Alnicos are more common and they supposedly used ceramic in series 2 according to a post on the web, but nobody has ever seen or had them. I had 16 Altec Alnicos back in the day when I was chasing his tone seriously. Its the Freq. response that you should be concerned with. Thats whats gonna get you the RR sound. Plus Randy was using Altecs in the early days of Quiet Riot, which would have been Alnicos for timeline. Bill from Great Plains audio is a great source of info for dates. He would probably know better on when and if the series 2 ceramic came out and the numbers they made.
Edit: There is also a Series 2 on Ebay and that is Alnico. I think Art is mistaken, but if he can provide proof then I'd believe it. I think Kelly would have known for sure though. Also check this link on the Altec brochure. Nothing about cerramic.
417-8h spec