battery drain since radio

I have a 2004 chevy tahoe in which I had a pioneer avic d3 navigation unit installed with backup camera.  Ever since install my battery dies every 7 days or so after truck is not driven.  My battery is good and alternator is good.  Week before last I had the metra gmos 04 in my truck changed thinking that could have been the problem.  Well since then my battery has died again.I took to the dealership yesterday and they said I had a 765ma draw.  they said when they pull the radio fuse the draw goes to 16ma.  Any suggestions?  I am taking truck to installer of radio tomorrow and see if they can narrow problem down.  If I drive my truck every 5 to 7 days I have no problem with the battery it cranks right up.  But if I let it sit that long, my battery dies.

sound like they might have something connected wrong. Check for a draw when the vehicle is tuned off and turned on. it's obvious that you have an issue with the install. 765draw is a pretty big draw. check the install."dont ground out!"

I think I found the problem to my battery draining.  Took back to installer today and trouble shooted for 1 hour.  Even unhooked radio completely and still had a large mliamp draw.  Come to find out we checked the stock bose amp fuse.  What was happening was the amp was not powering down even when vehicle was off.  Installer tied the amp power wire into a relay and the ignition wire so the amp will only power on now when the ignition is on.  After he did that we checked the draw and it was great.  So I hope that solved the problem.  I am going to let the truck sit until next Saturday and see if I continue to have a dead battery after truck sits that long.

either you have several vehicles or you just dont go anywhere.. i have never, in the past 16years been able to let a vehicle sit more than 2 days.. good job on the diagnosis

yes 7 days man thats longnever stop