04-10-07: Benie
I have 4 pairs of the early gray riser Siemens( some call them gray plates) and all have the codes on the glass but one.
But they are ECC88 not CCa, although CCa are said to be the pick of the litter from ECC88.
Benie, I have owned Siemens E88CC (not ECC88) grey riser tubes, and they are EXCELLENT (and inexpensive...relatively speaking). In fact, they are my second favorite Siemens tubes next to CCa. Yes, you can hear the difference between CCa and grey riser Siemens E88CC, but for many people (myself included) the higher price of the CCa is not worth the expense for the small tonality gain over the E88CC grey riser tubes.
FWIW, to my knowledge, all Siemens CCa are E88CC/6922. Any E188CC or 7308 being sold as CCa are not CCa at all.