Am I missing something? Your battery is being drained and this means it MUST be the radio? What - no need to check anything else, just replace the radio and amplifier for $800 and all will be well?

Or am I not understanding something?

Again - If someone did not get in there and MEASURE THE CURRENT and watch it go to ZERO when the radio or amp was unplugged, you have not proven what is draining the battery.

Take the damn thing to Troup Electronics in Jackson (the Motorola shop) and tell them you will pay their guy Greg Richardson to grab his meter and PROVE where the current is going. Be prepared to pay $95 or so an hour for up to two hours for him to figure this out. THEN you can go buy what you need.

I know Greg personally, call down there and ask him to do it at home for, like $50 an hour!!!
Tell him that Mark in Georiga sent you.