Before i pull my dash apart and see that it doesnt work....can i change the location of my head unit to be on the bottom of the "stack" and have the tray on top ,as i want to mount my gps unit above the stereo if i can swap it around....

Yes you can. Just unmount each from their respective brackets and swap.

cheers ...thanks for that...now i can go ahead and mount the gps lower and out of sight rather than sticking out like dogs you know what...on the screen....