Folks: Anyone know the casting numbers for the 300J and Ram 300K heads? I think these are spelled out in one or more of the older Mopar Performance magazine/specialty books I have seen, but am having trouble locating this in the mess called " My Archives" . I believe these are different castings from the 413 340/360hp 4 barrel heads, to accommodate the 1.74 exhaust valves (like the 915 and 906 440 Magnum Heads). Any help on this , including other differences like number of valve cover bolts (4 versus 6), rocker stands (needed or not), etc. would be appreciated!! Thanks, Keith