I just pulled off a motor a pair of 1968-70 340 exhaust manifolds and saw these do not have part number or dates cast into them. One one manifold, there is the correct 2863553 part number, but the number is one the backside and stamped into the iron itself? Looks unusual and can't say I've ever seen it that way before. Is there any reason why these would be that elway instead of numbers cast into it? I have an iphone 3 so I can't load pics yet. Any info please.