if the HU is in without mounting sleeves... there still should be a plastic trim cover that goes with your HU... its just basically a plastic ring that goes around your HU to hide the gaps.
basically something like this:
http://cgi.ebay.com/Eclipse-Trim-Ring-Cage-Can-Brackets-CD-Player_W0QQitemZ5839520262QQcategoryZ1498QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
its the black plastic thing.
basically something like this:
http://cgi.ebay.com/Eclipse-Trim-Ring-Cage-Can-Brackets-CD-Player_W0QQitemZ5839520262QQcategoryZ1498QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
its the black plastic thing.