I've never seen parts so hard to find online as the Montesa's I must say! I can't find an All Balls kit or anything. Hoping someone here knows the bearing numbers on the 4RTs for rear and front wheels, I think I found that they are 6004-2RS but says to double check your bearings first, before I go pulling anything apart does anybody know offhand? 

6004-2RS (in the parts list)

You must be doing something wrong as normally dead easy to google. As above full parts are available.

Quiet a bit of chassis parts are also common with the 315 especially rear suspension