You're right about the 5 years bit, but from what I could tell, nobody actually located and published that information, and this was the only thread that really talked about it. So I figured I'd add my findings for future folks looking for similar info.
As for the model, it looks like the
Kindle Touch and my
Paperwhite 3 are both using the same X1-ELOM modem, so the pinout will be the same.