C20let transfer box question

[bazzap8389]

Can anyone tell me what this bit is for on the transfer box. Looks like it's been cut and sealed together.

http://i660.photobucket.com/albums/uu329/bazzap8389/Mobile%20Uploads/649094E2-7EA5-4F2C-A819-3D0265FA0D2E_zpsemxcdwvy.jpg (http://s660.photobucket.com/user/bazzap8389/media/Mobile%20Uploads/649094E2-7EA5-4F2C-A819-3D0265FA0D2E_zpsemxcdwvy.jpg.html)

http://i660.photobucket.com/albums/uu329/bazzap8389/Mobile%20Uploads/2EC71686-1A7D-4174-B469-5A92E544C61A_zpsttecfgah.jpg (http://s660.photobucket.com/user/bazzap8389/media/Mobile%20Uploads/2EC71686-1A7D-4174-B469-5A92E544C61A_zpsttecfgah.jpg.html)

[nova_stee]

Its were the feed from the pump would orignly go. When they have a locking ring in people just squash them and use it as a filler

[bazzap8389]

Thanks very much! I was told it's a "locked diff" so I take it that's the locking ring then?