where to mount rear spoiler on 73 duster

Have you already bought the go-wing? They should come with instructions and location measurements. They require special brackets to be mounted in specific locations under the bottom of the deck lid and placed inside holes cut into the underside sheet metal. Does your deck lid have the factory provided holes? If not, places that sell the go-wings also have available a set of plastic templates molded to the shape of the deck lid so you can easily mark off the cut lines and drilled holes' locations. It can be tricky.

Jerry