D130AS 15"...what does the "S" indicate?.

Hi,
I have the same thing in a pair of early SUNN pa type cabinets where the horn drivers, and the crossovers also carry the "S" suffix. I'm going to guess that these were made for SUNN, hence the "S".

Do yours have a metal dust cap by any chance? Mine do, as do all the others I've seen installed in these old SUNN's. I've seen comments in which it was proposed that these would have been reconed as D130F's, but I'm begining to believe that rather than a recone, these were originally issued this way. I bought mine from the original owner who at the time claimed they had never been out of the cabinets.