rear axle shaft dust plate?
 

hey guys, i am in the middle of rebuilding my rear axle. i went across town and pressed out my shafts and got my new longfields pressed in with new bearings, seals, etc. small problem, looks like i forgot to get the little gasket, backing plate things off the old shaft that is sandwiched between the shaft and the lug bolts. exactly how important is this little guy? because im pretty tempted to slap them back in as is. picture of one of the old shafts with backing plate in case im unclear.

https://cimg2.ibsrv.net/gimg/www.yot...7a0f2f9e8e.jpg