skipro3, I'm no audio expert myself, but I would HIGHLY recommend MB Quart speakers. I have a good friend that works at a stereo shop and I've listened to the differences between other brands, and nothing compares to the Quarts. Focal is also a good brand, and both can be found on eBay. I've been contemplating on the MB Quarts for my truck, but just don't have the coin. Also, here's my two cents on the subject, but I've read some compelling info that caused me to change my mind. DO NOT GET AFTERMARKET SPEAKERS FOR THE REAR OF YOUR TRUCK. You will be just wasting money. Basically the rear speakers are just for fill, and won't do you any good to get high dollar speakers. Don't waste your money. Instead, spend the money on a good set of front speakers, get an aftermarket amp, and get a deck that offers RCA outs with a minimum of 4-5volt's. I was looking for the website I got my information off of, but I tell you what, it really opened my eyes. Once I get back to my work computer, I can send you the web-site I found this information on. Basically the guy who threw the site together gives info on rear speakers and what they are supposed to do. His opinion, and I am a firm believer, is not to put the effort into replacing them. Put your money into a good deck, a good set of front speakers, and a reasonable amp. I personally have a Kenwood KAC 890 deck. It has a USB input for the small IPOD shuffle, or any thumb drive style storage device. It has hook-up for CD changer, it has Sirius ability, and it also has some kick-*** features. Find it here at:
http://www.kenwoodusa.com/products/ListProduct.aspx?k1=2&k2=46&k3=172&pr=2357
I have an old Soundstream Reference 604 that is four channels. the website I'll give you more info on indicates that you can run all four door speakers off the front channels, and then use the rear channels for a sub or something. I personally have a dual amp set up because I like the ability to turn down the rear door speakers when I have sleeping kids in the back seat.
DRURY seems to have a kick-*** setup. Way better than mine. He might agree on the necessity of the rear speakers. Not too sure, but you should try it before shelling out the do-ray-me for the rear door speaks.
Sorry to get so wordy. I've always kind of been into the stereo stuff.