318 forged crank question

The 318-3 is what Chrysler called there industrial engine like the were used in Motor homes. Had a lot of differences to the ones used in cars and pick-ups. The fact that this one says 318-3 on the end of the casting number has nothing to do with it being a 318-3. The only 318's that for sure were steel is in 67 back 318's. I'm sure they were found in them in later years here and there.