Metra 82-7500 Speaker Mounting Brackets
2003 Honda Civic
Ended up trying to use these with 6.5" speakers, and was able to make it work. Installation in the 2003 Civic Sedan rear deck was not as simple as I would have liked, but given I was using 6.5" instead of 5.25", I can't complain. The holes to mount to the read deck were right on. Would be nice if they were recessed a bit with the flathead screw that sits flush with the top of the bracket. This would make for a perfect fit for both 5.25" and 6.5" speakers.
Pros: Holes all line up as expected. Can't beat free
Cons: Screws for installing to rear deck don't sit flush with top of bracket.