its not very hard i've done all the speakers in my 04 ext cab. the doors just have a bunch of metal clasps. the plastic that the metal sits in isnt very strong so dont be bummer if one or two break. just be gentle with the door panels when pulling off.
You make life rough on your motor, your motor will make life rough on you...
@tsduke, I did the same as you and replaced the factory speakers. I was going to replace the stereo but the wire harness and stereo kit you have to buy for our trucks are expensive. I have priced them for a 05 Chevy Silverado 1500 and the wire harness is $80-$90 and kit is like $20. That is over a $100 before you buy a stereo. My factory stereo does not even have a CD player, I am looking to buy a factory stereo with a cd player.