Pair of Chevrolet big block oval port cylinder heads. Casting number 3872702. Casting dates November 11th and November 18th. These heads were pulled off a running motor. I recommend inspecting and rebuilding if necessary before installing. I removed the retainers on one chamber to inspect clearance between valve stem and guide. It was.002 closed and .003 open. One head has one threaded hole on end of head chipped as pictured. This will not affect bracket mounting when this side is installed to back of motor