2008 crew cab speakers

I am trying to make a list of what all I will be buying to replace the factory stereo and speakers when I do get around to changing it and I'm trying to get a size on the door speakers.Crutchfield lists 2 different sizes,5 1/4 and 6 3/4,which ones do I need?If one size will fit both sets of doors that will simplify ordering so which size fits all 4 doors?I'd like to get all this info without having to pull off the door panels so if anyone can chime in here and help me out that'd be great.

2008 Silverado crew cab 4x4 LT w/Onstar

I am trying to make a list of what all I will be buying to replace the factory stereo and speakers when I do get around to changing it and I'm trying to get a size on the door speakers.Crutchfield lists 2 different sizes,5 1/4 and 6 3/4,which ones do I need?If one size will fit both sets of doors that will simplify ordering so which size fits all 4 doors?I'd like to get all this info without having to pull off the door panels so if anyone can chime in here and help me out that'd be great.

2008 Silverado crew cab 4x4 LT w/Onstar

I would pull off the door panel and see how the frame is fabricated for the speaker mounting.

On my 2000 silverado the cheapo mexican speakers are the poorest of quality. I did some extra work and used the existing connector from the OEM speakers and mounted it on the new replacements. I used the 51/4 inch size. also the speaker was set into a plastic craddle which I dumped. this is why you could use a slightly larger sized speaker..

with a high quality speaker the sound will have no distortions. try to get 6-10 ohm speakers if possible for use with GM audio equipment.

GM uses cheapo very small guage wire , NOT good for the low frequencys...............should have used 16 ga .

There is connectors that you can get for connecting aftermarket speakers. The ones that I got were from BestBuy. But you can also get these connectors from Crutchfield along with what the speakers sizes are.