I have a problem that I need help with. I have a engine manufactured in 31'. The rear main bearing cap is slightly different than ones I have seen before. This is a little hard to explain. If you look at it from the side, the mating surface that goes against the shims, there is a step in the surface, about a quarter inch long and one eight inch deep cut at the very rear of the bearing were it mates to the aluninum oil shield in the upper block. I other words when I bolt up the rear main there is a eight inch gap vertical and one quarter inch long horizonal on each side of the lower main cap just below the shims at the very rear edge of the main towards the flywheel. Has any one encountered this before? What is this gap for and what do I put in it to prevent oil from coming out the gap from the crank slinger. Other than this the main is identical to original. Any help you can give me would be much appreciated !!!