MAIN BEARING SET STANDARD Part # A-6331-STD Model Year 28-31 $85.00 SET. Modern insert bearings if you are changing your motor from poured babbitt to inserts. Kits come with instructions. The block MUST be machined to accept these, they are not a direct replacement for the original babbitt. You will need to purchase 3 of the A-6332 thrust washers to complete this job. Standard size. U.S.A.