What the OP is referring to as Gen II is what we call Gen 1.5 - the 2013-2016 24kwh pack. Even though the chemistry was changed in April of 2013, the actual case seems to have been changed with the other modifications from the beginning of 2013. Not that I would recommend using an early 2013 pack as a replacement! As I understand it, an adapter kit from Nissan is required, and the lack of a battery heater in the 2011 is a further complication.
Scarlet Ember 2018 Leaf SL W/ Pro Pilot
2009 Vectrix VX-1 W/18 Leaf modules, & 3 EZIP E-bicycles.
BAFX OBDII Dongle
PLEASE don't PM me with Leaf questions. Just post in the topic that seems most appropriate.