When I get new bearings, Do I just get some main bearings, and piston rod bearings and put them on, or I have to get a certain bearing to go on each part of the crank, and a certain bearing for each piston rod? I see on the piston rod that there's numbers ( 1, 2, 2, 2) Do I have to get certain bearings for each number? and same for the main bearings?? thanks