UnrealPak is a native .pak package creator from Epic Games itself, the program in question is a binary which UE4Editor calls it during the process of packaging a game, or .pak files, Rules mostly apply as the same like the u4pak, exceptions begin that no Python is needed. The Nimbus folder needs to be included into a new root folder above it with the name desired["Your Project"/Nimbus/Content/Vehicles/...], and you will need to drag the folder one by one, instead of running the .bat. The tool is very versatile of allowing packaging options, a difference from u4pak, is that the tool allows you to compressed even more the current .pak file, reducing the size better, but it will result in some side effects when datamining user skins on AC7 Mod Tools or packaging with 7z compressions, so we recommend the no compression one instead.

(NOTE : Don't redirect the tool outside of the structure it originally comes[Engine/Binaries/...], otherwise UnrealPak when it starts on another directory, a Engine folder will be created each time on the root of the most used HDD of your system, thus why this package comes with this structure, to avoid side effects like that to occur)

UE4 Light Builds :
https://onedrive.live.com/?authkey=%21AEqtvAaZEWJbUGI&id=674105528DB48D93%21112&cid=674105528DB48D93