numbering system on sovtek tubes

I replaced the sovtek 6l6s on my 65 blackface with groove tubes. The guy at the store sold me gt 6l6s #7 and said they would be close enough to the ones I had. He went by the numbers painted near the base of the sovteks.Those numbers were 00 08. By those numbers he concluded that #8 groove tubes would match but he only had up to #7. Since then I have seen sovtek 6l6s with the number 03 14 on them. Do these numbers on the sovteks relate to the groove tube rating system at all?