Installing a 1972 A Body Manual steering box on 1973 Duster

All A-Body manual steering boxes are interchangeable and are small sector. The change in 73 on manual steering cars was the pitman arm, center link & idler.

So... if your 73 has manual steering now, you need to put your pitman on the 72 box.

If your 73 has power steering it has a large sector Pitman arm & you would need a pitman arm for a manual steering 73 & newer (or change the idler,centerlink, & pitman). In this case I think you would also need an adapter between the box & steering shaft.