I found someone on the bay selling these
GE 5670 Red 5 Star tubes and grabbed a pair....they were advertised as rare so I decided to try them-really great sounding tube, they sound like a perfectly laid back version of the GE tube I got from another AC member. So far I've grabbed about 7 or 8 different tubes that fit my GF Tube DAC-09 and these so far are the best I have heard. I don't know any specifics about the construction but I know they sound nice, really nice. One caveat is that the seller took almost a month to get the tubes to me and had various excuses for the delay and even sent me two additional Sylvania 5670 tubes to ease my pain so just a heads up if you pursue them, based on feedback I think my case was isolated though.....PM me if anyone wants specifics or a link to the listing.

Below is listing info for those curious about type of tube-
5670 396A 2C51 GE~3x MICA~RED LABEL~STAR~TUBE AMPLIFIER
BLACK PLATE~TRIPLE MICA~D GETTER~RED LABEL~5 STAR~RARE!