Head Stock Bearings - Montesa - Trials
I replaced the upper bearing on my '`07 4Rt last month. So nipped downstairs to check for you. I took original bearing ( Nachi brand) into a bearing shop. They had right size in two different brands. Played it safe and went for the genuine replacement. Bearing is Nachi taper roller 32005JS/26. I dont see there being any change between 07 and '`12.