I had a set of those only Duster back in the mid 80's. When you get rocker shafts for them, make sure the oiling holes line up to the arm hole when the valve is closed. The mothership screwed up on them and didn't correct the issue. I got shafts from Ed Hamburger, before he went GM, and they were wrong too[ probably just reboxed mopar]. I found out the hardway that the holes only lined up when the arm was almost vertical. Tatered some bushed rockers and pushrods. Found out from a knowledgeable source that it was a factory screwup that didn't get resolved. If you get rollers from someone with shafts you will probably be ok. At the time, you could get bushed or non bushed iron units from Mopar or Norris made a really nice set of stainless rollers with shafts but like a dummy I didn't get those. Could have gotten a smoking price too since my boss bought direct from Norris. The pushrods, at that time, were the semi finished ones that you cut down, after measuring what you needed, then pressed in the cup end for the rocker screw.