Front doors speaker size: 2007 C4500 LLY CC

Has anybody gotten far enough along in the ongoing engine repairs to be able to afford aftermarket speakers and sound system.
My 07 lly with 308268mi has finally graced me with some reliability after a new injector fuel pump was installed (Thank You John Prejean and Service Chevrolet Lafayette, LA)
So im up for sound system upgrade.
Many thanks to all
Tatuzinho

6.5

Thats the size for the main speaker at the bottom, there is also a tweeter set farther up in the door panel, i didn't measure it