Why no Top Shaft Spacer on a MR ?

[Dandare]

I've been stripping my g/box on my Rat in prep. to make it brushless proof & noticed when coming to re-assemble the slipper assembly, unlike my x2c there is no top shaft spacer between the bearing & slipper plate (part No. 125001120) on a Mad Rat, though i can't see any obvious difference in this area between either an x2c or a MR, therefore the slipper plate sits directly against the bearing

Is there a reason why this part cannot be fitted & why isn't there one there, lol ?

Dan.