hp383, this is a cross bolted main block. A dodge dealer on the east coast was one of the ones ordered to close and they liquidated all their parts. I bought the MP (World) bare block for less than half price and built a 512 out of it. Had issues with the releif valve sticking when I ran it on a friend's dyno and had to change the pump out. I'll touch up the block before its all over with. LOL Do you think the extra little rise caused by the diesel mounts will help the header clearances??? It has about 8 dyno pulls and 500 road miles on it already. Friend couldn't afford the 67 Coronet with the motor so I pulled it and we put in a mild 440 and he is happy. And I will be happy; might take a while but the work keeps me occupied; better than sittin in the rockin chair