Yes. The manual OR the power. The idler arm is different though.
I slipped a steering box from an 88 Dodge Diplomat into my FrankenDuster. The steering boxes interchange through many years and body styles. The trick is whether it is a small spline for the pitman or a big spline. I've read that ALL C bodies had the bigger spline but that the A body line didn't get the large spline until 1973.
In short, your swap is a sure thing.