Honda Fourtrax 300 Rear Differential spacers

Doing some maintainence on the 300 (yes again) and have the rear end completely dissambled. Got to the diff, splited the cases and started cleaning. Got it all shined up only to find out that their are supposed to be 2 spacers either side of the ring gear. I managed to find one, whether it was the only one that came out or I managed to lose one in the process.

How important are these? I know it sets the backlash? Between the ring gear and the pinion, but is it really going to matter? And if it does matter how do I know what size I am going to need? I know that they dont share the same size either side of the ring gear which will make it harder. And the parts list online is really not helpful, I think their are about 20 different variations listed under the same part number.

I appreciate all the help.