Rare, matching date code, tested as new pair of 12AX7 ECC83 with long plates, copper grid rods, slant D-getter with foil, and criss-cross top. Personally, I think this is one of the most musical sounding 12AX7 ECC83 ever made.
The bottom code "⊿ M mCN" denotes that both tubes were made in the same month of October 1954 at Philips' plant in Heerleen, The Netherlands. Both tubes are branded Valvo, although the printing on one tube is almost rubbed off.
On a TV-7 D/U, where the minimum acceptable reading is 32 and new tubes usually test at 48 or higher, these two tube tested as new at 53/53 and 52/58 respectively. They were briefly tested in a preamp and were quiet and worked fine.
Price is for the pair.
Worldwide shipping by SpeedPost (express) US$40. Shipping by regular airmail (takes longer) will be cheaper. Please ask. Happy to combine shipping to save you shipping cost.
Questions welcome.