Many times I've asked, and been asked, "Is that a 400 or a 440 and how do you tell the difference?". Of course there is the text book answer, "Look for the number stap pad located here and there." The only trouble with this method is that those little pads can be VERY hard to see, especiall on an engine that is not exactly clean. Because I have a few cars and more than one example of each engine, I've noticed a far easier way of determining if a big block is in fact a 400 or a 440. http://imperial.point2this.com/nybml/m-r/400vs440/index.htm