After doing a TON of research on this for my 2013 leaf SV, it appears that the newest part, superseding the older ones is 283B0-3NF2B, the FCC ID on this (from looking up other parts with the same lookup code - 283B0P) is N7NSL8080, this contains the Sierra wireless SL8080 modem, which supports 4G bands. The pricing is the same as the previous model, and they both show compatibility with the 2013-2015 leaf SL/SV. It looks like if you request this part number for the upgrade, you should be in good shape for 4G from everything I can see about the chip it uses.
https://www.nissanpartsdeal.com/parts/n ... 3nf2b.html
This is the part with the same lookup code where I was able to see the FCC ID:
Here's the official leaf part, kinda hard to read, but it's the same FCC ID: