Since there have been a few recent posts asking about installing speakers I thought I'd write up my recent install. It should answer some questions and save people some time and money.
There are a couple of options for new 4x6" speakers. I decided on a pair of Polk db460s I found on eBay. They got some decent reviews and they are "marine certified" so water damage isn't a problem. When I tried to install them I found out they have the same problems a lot of speakers seem to have. They didn't have the right mounting holes and the tweeters stick out too far to flush mount them. Fixing things is pretty cheap and easy.
Here's a quick writeup of how to modify and install the Polk db460s but it should be useable for other speakers with the same problem.
Remove the stock speakers from the dash.
I ended up folding the windshield and pulling the dash out. There are lots of threads about this. Here's a good webpage describing how to do it.
Remove the plastic rings from the old speakers.
Use a razor or xacto knife to separate the ring from the speaker. I also used a heat gun to soften up the adhesive. Be careful to not to damage the rings or melt them if you use a heat gun, you're going to use these as spacer rings. Clean off all the junk from them.
Drill New Mounting Holes.
Put the old speaker face to face on top of the new Polk. The Polk db460 almost fits inside the stock factory speaker. Use the old speaker as a guide mark the hole location on the new speakers with a marker or pencil. Separate the speakers, center punch where the marks are and drill the new holes. I used a slightly larger drill than what fit through the mounting holes on the stock speaker.
Mount the spacer rings on the new speakers.
Using a hot glue gun, contact cement or other general adhesive attach the spacer rings from the old speakers to the new speakers. Be careful not to get glue on the rubber surrounds.
I put 4 drops of hot glue on the cardboard mounting ring. A quick alignment and some slight downward pressure and the spacer rings were mounted.
Add the speaker cloth.
Using a hot glue gun glue some speaker cloth to the spacer ring. Glue one side, let it set then put some glue down on the other side and stretch the fabric before attaching it.
This is an optional step. I had some black cloth hanging around and wanted to cover up the shiny cones of the Polks.
Mount the speakers to the dash.
Wire up the speaker. (I used a Metra factory wiring adapter from Circuit City.)
Put 3/8" nylon spacers on the mounting bolts.
Slide the speaker on the bolts. Make sure the wiring side is down so the terminals are accessible if you need to get to them later.
Add some lock washers and 8-32 nuts. I recommend not reusing the factory nuts. For those of you who don't fold the windshield wing nuts work well.
You don't want to have to open things up again just to tighten some nuts so use some thread locker (Loctite)
Tighten up the nuts.
Reassemble your dash and windshield.
With the spacer ring and the grill cloth the Polk db460 tweeter sticks out just a little too far. If you tighten things up the tweeter will push the metal grill out just a bit. If this bothers you can add some washers next to the nylon spacers on the bolts.
Total time to do this once the windshield was dropped was under an hour. I got the spacers, the #8 lock washers and 8-32 nuts from my local True Value hardware store. The wiring adapter is a Metra 72-1002 Speaker Harness. (Circuit City or partsexpress.com) Using one means you don't have to cut/solder/crimp anything to use the factory wiring. The db460s have been replaced by the db461s. I'm not sure the tweeter sticks out the same amount. If it's more you can always pull the grill off the tweeter.
While the windshield was down I ran some wires for some future dash mounted tweeters.
That's it. Pretty fast and not that complicated. The speakers sound pretty good for what they are. I'll be adding some dash mounted tweeters later to improve the sound.