I appreciate the information Randy, it does make sense. Like looking down your sights on a gun. Close one eye and the sights are off set, look down with the other eye and they are dead on. Being that this motor is one of the earliest models of the 283, made in 56, issued in 57, I would be comfortable in saying that would be the most likely reason for the two tabs. Even the motor mounts are different, located in a different spot than later model 283's/ V8's. I've read here and there these early motors had various quirks others didnt have so it comes as no surprise that the tabs would be setup that way. Thanks again Randy.