72 valiant ex man.
Disclaimer: I am not an expert on all things MOPAR.
The numbers posted above are correct for my 72 Dart Swinger, I just checked them.
The difference in casting number is likely because the left side, drivers side, is inverted and a special part for the A body. The B body I'm assuming has more room and thus doesn't need the special inverted manifold.
The pistons I pulled out of my engine all had the rings froze up on the drivers side bank of pistons, all of the rings on the p side were freely moving. Too much heat because of the inverted manifold.
I have a perfect set that will not go back on this car as long as I own it.