I just rebuilt my valve and best recollection it’s glued into the valve side but threaded
MPT FPT on top. So slip connection into the valve, and FPT thread on the inlet. The Quik Stop black lever part can be replaced with a new rubber gasket if it’s leaking, just remove with a Phillips head screw and pull the assembly out. You may need to also remove the valve top and unscrew the FPT side to get at the stick 'stopper'. The stopper gets chewed up if you engage it while the gears are spinning, so it's a replacement item.
See image
https://sep.yimg.com/ay/yhst-130870...top-feed-valve-quikstop-assembly-522802-6.jpg