where to mount rear spoiler on 73 duster

i am getting one from rtl accessories here are the parts should i still have to cut trunk to mount,Here we have a brand new reproduction Go Wing Spoiler for your
1970-1974 Mopar muscle car.

This wing will fit the following cars:
Challenger, Cuda, Charger, Dart, Duster, Demon, Road Runner and
any other Dodge or Plymouth.

This kit includes the following parts:
-Spoiler Blade
-Spoiler Pedastals and tightening bolts
-Pedastal Gaskets
-Spoiler to Pedastal mounting brackets
-Mounting bracket screws
-Spoiler to Pedastal rubber gaskets
-Pedastal adjustment bolts and nuts