I have both Bose and standard replacement 10" rear deck subwoofers for 2000-2005 Devilles. These are OEM. They are used in good condition, ready to install and enjoy.

Standard ($99 shipped):

2000 2005 Cadillac DeVille Rear Shelf Subwoofer Speaker 16246789 | eBay

Bose ($75 shipped):

00-05 CADILLAC DEVILLE DHS 25722341 REAR DECK SPEAKER SUBWOOFER SUB BOSE OEM

Contact me through the product page on ebay before purchase and mention this forum to get the standard woofer for $85 or the bose woofer for $70.