what speakers fit in 2002 GMC Envoy?

I want to improve the sound over the stock system I currently have.  What speakers fit both the front and rear doors in my 2002 GMC Envoy with no or few modifications?  Does anyone out there have access to software that tells the dimensions of the speaker locations such as size and max depth? The online sites say either 6.5" or 6.75", but that leaves me confused on the right size.

I'm also looking for recommendations on coaxials in the $100/pair range that are a good value.  I will run an amp, 4 channel 200-300W - i need a good suggestion in the $200-$300 range.  I don't have any good shops in my area, so any and all help will be appreciated.

Thanks guys!

go for 6.5" all around.  You'll need some adapters like these in order for them to fit properly without major modifications.

I too highly recommend checking out Crutchfield's web site.  It's nice cuz you put in your vehicle make/model/year and it will filter out all speakers that do not fit.  Also, they measure the tweeter protrusion, bottom-mount depth, and magnet diameter in addition to the overall diameter, to make sure that your aftermarket speakers will definitely fit.

Compared to a retail store like best buy or circuit city, crutchfield is pretty darn good since they give you just about all of the installation accessories for free, as well as some pretty decent install instructions.