Background: Thinking about building a Champ 5C1/Silvertone 1301 kind of amp. I have a PT but I don't think it has 5V, so I was keen on a 6.3V octal recto - octal for the visuals, to match the 6SJ7 and 6V6. I have a couple of Brimar 6X5GT/EZ35. Word is, the early 6X5s are an accident waiting to fry your PT, and that the later Brimar type with the offset anodes is much better. But these ones don't resemble either - they look more like a 6X4/EZ90 in a big octal bottle. Which is probably a good thing - just struct me as a bit odd. The code is 3F2/432 which is 3 week of June 19x2, type 6X5GT - three digit type code implies 1952. In 1962 it should've been 1432 - they're priced at 12s 6d som they must be pre-'71. Anyway - has anyone seen 6X5s like this before? Can anyone confirm that they're 6X4s (EZ90s) in a big bottle.