School me on 70 Duster 4 speed shifter handle please

The type of mounting of the handles to the shifter is one thing that you have to pay attention to. The 71 and earlier handles were the bayonet mount push in style. The ones after that were the bolt in style. Check out Brewers site for some details.
Brewer's Performance - Mopar A833 4-Speed Transmission and Component Specialists