What leaf spring should be used on a Chevy Nova?

Firstly it depends upon the year. Older cars used the monoleaf which is extremely hard to find (last time I looked). Listed replacements are the more conventional multileaf type. When my '63 broke one, I found a very low milage one resting in a farmer's field ! It was $10 ! A few years later I had it, and the other side, re-arched at a spring shop.