There is a slot on that took kits main body thats used for the upper hand guard/gas tube lever.
Those kits really are a wonderment of design and thinking. All my AK's that came with a "standard" stock came with one, including my WASR and SAR. If you havent looked in the butt trap yet, you may want to. There could well be one in there. Those trap doors are a pretty slick design too.