This set was taken from an Interstate model and installed on a Tour model.  The power plug on the radio was cut off and the three wires spliced in.  I believe they are Green=Ground, Red=Battery Hot, and Red/Black=Switched hot.

The mount plate for the switch assembly was fabricated by the owner doing the conversion work and may (or may not) work for you.

I believe everything is working as it should, although I don't currently have the ability to test it.  This unit has been sitting on the shelf about two years.