Bearings in the gearing

[Duffis]

Hi!
I got a bearing by my gears in the carter (piaggio LC DD) and i need som help to find out where I can buy gears to it. I have a carter wich i have gearing that fit, but the carter with the bearing in it is a bit tighter so the gearing does not fit.

Is it a special year they had bearings by the gears or is it a special model?

Thanks.