One the things Amazon/Lab126 has been doing is consolidating firmware builds (so the same version runs on multiple devices).
Currently (of touchscreen devices):
K5 - never yet been touched by the 5.6.x series (and now we know why - TTS is an extra cost add-on rather than built-in).
PW-1 stalled at 5.6.1.1 (which is what the PW-3 first shipped with, even thought they are different processors/SoC devices)
PW-2, PW-3, KT2, KV (and maybe Oasis) have a common firmware version.
The K5 and the KT2 have the same ir touch screen scanner.
The PW-3 and the KV have the same screen (I think it is a very nice, clear display - I like mine).
And what we are calling the "KT2" is technically the K4-2 (second gen, K4 - IR touch screen replacing the buttons). Open them both up and lay side-by-side, you can see it.
But I could just see people typo'ing that as the K42 (the 2036 Kindle model).
So KT2 it is (second Kindle using the IR scanner touchscreen).
Just get back on the horse if it throws you - you will not be thrown too many times before you get the hang of it.