What is the 2003 chevy avalanche speaker size?

The 2003 Chevy Avalanche comes with 6 3/4" speakers standard in the vehicle. This is not the most common size so You will need to use an adapter to fit the more common 6 1/2" speakers into Your truck. Upgrading the speakers is a great way to improve the sound quality in Your vehicle. If You want to get even better quality I recommend adding a dedicated amplifier for the speakers in the doors. Another way to get great sound quality is to change out the head unit for a newer model. These newer head units have more control over Audio quality and can also add more advanced features like Apple CarPlay and bluetooth to Your truck.