Subaru RG3200iS Conversion Kit uses an adapter that makes it possible to operate an engine on three different fuels Propane, Natural Gas, and Gasoline. Adapters will mix the Propane or Natural Gas into the air stream above the gasoline carburetor. The gasoline carburetor remains basically untouched. So this kit is not a conversion, it is an adaptation.

http://www.centuryfuelproducts.com/generators/conversion-kits/subaru-robin/rg3200is.html