have u tried a google search on the part number?
I tried the HPI 2-spd pinions form Tower Hobbies and they worked just fine. They are made of steel and cost <$10ea. However, I would not use them on a big block engine as they use the smaller MT2 size bearings.
kind of a fair point, the steel cen bells and bearings dont last as long with a BB, but theyre not all that bad - in my experience anyway. there are ceramic bearings that should work out better on ebay, but i havent got round to trying them yet. anyone else tried ceramics?
an alloy 3 shoe clutch setup seemed to help my bearings last a bit longer - less slip, less heat i guess.
rambling, but it might help... and for gods sake dont use plastic shielded bearings in ur clutch... trust me on that.