I have a pair of small block mopar heads on a 360 engine that I cannot identify. The block is from 1979, the intake manifold is 1969ish, so no real clues there. The heads are cast iron and do not have the typical 7 digit casting number under the valve cover, nor do they have the typical 340 or 360 casting number. There is a 16M cast into the top of one of the intake runners where the 340 or 360 would normally be. There are a few other small markings, the number 74 and a time clock symbol but that's about it. Could it be another manufacturer other that Chrysler? The motor is still in a running truck, so I'm a little limited on the info I can provide.