ARB RD99 - Manual (Page 19)

3 Installing the Air Locker
17
Install the spring clip by first hooking both ends of the clip into the
small aligned cutouts of the seal housing and the adjuster nut, and
then snapping the clip into the groove of the seal housing using a
screwdriver. (Fig.9.)
Figure 9.
Check that the seal housing is now secured from rotating and that it
is still sitting flat against the adjuster nut.
IMPORTANT:
Check that the tail of the adjuster nut locking tab does not
push on the seal housing. Bend it up away from the seal
housing with a screw driver if necessary.