I am new to Altis Life editing and such and also have this issue. I swear I have un-packed every single file in the Arma 3 folder but I can not find where the classes for the backpacks are. I am trying to edit the maximumload of the backpacks to increase their carry weight in the Altis Life. Been stuck on this for about 2-3 days. Would anyone be kind enough to point me to the exact file I need to alter this?