I have just rebuilt the bottom end of a mates motor and he brought all the bearings from our local British bike shop I have been dealing with since 1978 BJs in Brisbane the main bearings are NSK bearing NJ306EMC3U537 made in Japan, they fitted very nicely and the crank went together pretty good on the box it also has NSKHPS and 507 under the bearing size, most bearing suppliers just go by the bearing numbers as supper bleand was just a name used at some time as Les has said.
The old bearings I replaced was still in great condition, not sure how many miles are on them but still look as good as the day they went in.
I marinate as well.
Ashley