NKT222 was used in certain Tonebender Mk3 builds, so that's cool. There does seem to be a lack of online info about this type. In addition to the equivalents listed above, other 2GT types (2GT102) are listed as a European type here (pg 134):
Transistor Equivalents - Handbook reference for transistor equivalents for substitution
archive.org
Can you get pics showing the printing we can't see or post the full printed text here?
It's a flanged TO-1 package (if that has its own name I don't know it off the top of my head), and not the thinner kind like you see on SFT* types. That can maybe point you in a certain direction. I've most commonly seen that on TI, Brimar/Thorn/Mazda, and Siemens transistors, but I'm not sure how accurately that reflects what's actually out there. I think most if not all the Siemens types I've seen like that had standard (not gold-plated) pins. The printing style is different from most TI types where the font is usually smaller, but it looks very similar to some. Here's a 2G302 I have, for example:
View attachment 53299
Note the serifs on the G in particular. Mazda/Brimar/Thorn types more commonly have colored sleeves, but here's a Mazda AC156 with similar printing.
View attachment 53300
The 2G302 has the TI logo printed on the other side, while the AC156 does not have any brand ID on it but it came in a sealed Mazda AC156 box so I'm pretty certain that's what it is. I wouldn't say with any confidence it's made by these companies, just throwing whatever info I can out there at this point.
EDIT: Actually, someone pulled a couple replacement 2GT182s out of a radio here. The pic is really low quality but these look a lot like Texas Instruments types here.
1961 Decca TP50 Debonette 6 transistor MW/LW portable Success Stories
www.vintage-radio.net
It's odd to not be able to find any info on it if it's a TI type, but maybe 2GT designates it as something sold in a particular way that results in little info. It's not uncommon to find transistors with house numbers or numbers printed on them for a 3rd party (there are a lot of transistors with Tektronix numbers printed on them even though they're made by a company like TI or RCA), and those ones would be less likely to make it into a transistor substitutes or transistor databook.
EDIT 2: OK these were sold as replacement types by Radiospares:
View attachment 53304
Taken from here:
AVO TT169 Transistor Tester Vintage Test Gear and Workshop Equipment
www.vintage-radio.net
You can see Made in England printed here. I believe Radiospares used various manufacturers, as you can find other transistors with different countries of origin.
