I recently picked up a pair of Altec 603Bs, and just after getting them, I found a pair of Altec 604Cs. If you are not aware, the 603B is similar to a 604C type driver without the compresssion driver, and has a similar multi-cell horn that is a bit larger then the 604s.
Am I actually holding onto the first (B001) and 67th (B067) 603Bs that were produced by Altec?