14n7.. not sure, and no worries, I'm learning the same here from this thread. And from the 6SN7 thread, lot of surprises, right when you think you read it all, lol. Some of those guys come out of the woodworks.
And yes there seems to be a dozen different tall 7N7 out there but of the dozen maybe half are from the same manufacturer. (O.o yeah I'm confused on that one two). Mainly Sylvania. Philco /National Union might be the one to design the JAN CBRZ for Lansdale distribution to the military. The only confirmed non Lansdale build to my knowledge is a General Electric 7N7. There might be others. If your new to the Frankentube, do a quick search on it, a user here at Headfi.org
@bcowen named this perticular Lansdale tube the Frankentube because of its flat head top. But I think you know about it already as you mentioned its about as good as a Tung Sol round plate. (Now I want a Tung Sol round plate) do you have any tall 7N7?