I recently bought a 08 rmz250f and guy told me the top end had less then 10 hrs on it, i mybe put 3hrs on it and then tore my acl at work. So i sold it to a good friend for his son. He put about 3-5 hrs on it and something came apart and cracked motor cases right in the middle of engine. Idk what came apart and if it was a part failure or operator error but i feel bad and want to help him fix it but i cant find a 08 motor anywhere. What years are interchangeable? Like will a 12 bottom end bolt to a carb top end . I really like to find a drop in replacement used. Ive never torn into one that deep before.