MA MOPAR did some strange things, I had a 73 and a 76 truck engines, the 73 had 6pak rods and cast crank, the 76[which is the engine I am using in my DART]had a steel crank and LY rods,engine was untampered with, had only 21,000 miles so I know it was factory. I have seen steel cranked engines in several instances from 73 and on...strange but true