There were stepsides made in the '70’s that will fit but theyre pretty rare and most likely rotted to shit by now. I meant the fenders that bolt onto the regular bed.
Have you ever driven an old Ram with a 318? I used to drive my friend’s '89 and it was the most gutless turd of a truck Ive ever driven. Barely did highway speeds, wandered all over the road and got about 7 mpg.