hey Himalaya,
yep, the shaft is about 8mm. The "old" motor didn't have those bushings, the shaft measured 8mm. So this one's diameter is a bit less then 8mm (8mm bearings). The bearing at the front endbell is a standard size, 8x5x16 mm, you get them everywhere. the back one is 8x4x15 I think. in my "old" losi, I 've replaced the bearings with ceramic ones.
I always had to smile, when people talk about the "big" (but actually small, regarding the power) bearings of their Medusas, CC-Neu etc... Mine is bigger, Size DOES matter
cheers
florian