Well to be honest it was orginally
A slant 6, not sure if there are different models with that... my dad bought the car when I was like 3 or 4 years old, so approximately 34 years ago. Anyways he pulled a 340 out of a Duster and bought the 340 hood, 727 trans etc and this is what it is now. So I don’t think I’m answering your question lol... I think every nut and bolt has been replaced. A guy in Nova Scotia has a shop and builds Mopars, he did a lot to get it to this point. Also it was in the garage for almost 30 years. It was just finished this past summer.