Broken Diff???

[dibble34]

Hello all

have a question about my front diff. Just rebuilt it, but broke part LA200 (11) can be seen here http://www.oople.com/rc/manuals/zx5/...s/zx50028.html. (it is the plastic washer thing that holds the bolt) I have managed to do the nut up without this bit in place. My question is should this be ok or do i need to order this bit? Will the diff fall apart without it? Sorry if this is a stupid question