Are you able to install a 2005 Bose 6 CD changer radio into 2003 Chevy silverado?

It's unlikely a direct plug-and-play installation of a 2005 Bose 6-CD changer radio from another vehicle into a 2003 Chevy Silverado will work. While both are Chevrolets, the wiring harnesses, mounting brackets, and potentially even the electrical interfaces (voltage, signal types) are likely different between the years and even trim levels.

You might find some similarities, but you'd almost certainly need an aftermarket wiring harness adapter to connect the radio's wiring to the Silverado's existing wiring. Even then, the physical mounting might be problematic without custom fabrication or finding a compatible mounting kit.

In short, while not impossible, it's a complex project requiring significant electrical and mechanical knowledge or the assistance of a professional car audio installer. It's far simpler and more cost-effective to find a replacement radio specifically designed for a 2003 Chevy Silverado.