Check out crutchfield.com they have all the info you need and have great customer service.

sonicelectronix.com is usually good for discount prices.

 

2ND for Crutchfield. They will send you everything you need to install and tell you if the speakers will fit. I just bought Kicker front and rear speakers from them and they are great. Make sure you check out there returns page its full of stuff that people didn't like once they got it and Crutchfield goes through it to make sure its is operational and then resells it at a big discount.

 

5x7 or 6x8 will fit the stock locations. If you have audiophile, then your fronts have separate tweeters. For the fronts, you can get component 5x7/6x8 with separate tweeters to replace factory, or you can scrap the separates and get 2/3-way speakers in the front. Crutchfield has great information and support. Its prices are generally somewhere between average and horrible.

With speakers, Crutchfield includes wiring harnesses. The factory speakers have a clip-on wiring harness the speakers -- you don't just have bare wires into spring clips. If you want to put in aftermarket speakers, then you either have to use an adapter harness or tap into the factory wiring (e.g., cutting off the factory harness to expose the + and - wires). I like to retain the factory harnesses, so I tend to buy my speakers from Crutchfield. I tend to buy my amps and subs elsewhere. Kicker makes good stuff at reasonable prices.

Good luck.

 

Bought two pairs of JBL Stage 8602 6" x 8" 2-way Speakers from Crutchfield back on 24 Aug 17 for $39.99 per pair. The speakers for your truck will likely be different because I drive a 2005 F150 regular cab.
Just checked, these speakers are no longer available, sorry. But there are a myriad of other speakers Crutchfield carries.