Upgrade Your Macbook Pro (SSD Upgrade, RAM Upgrade, Optical Drive Bay Adapter) - YouTube
MacBook Pro 15" Unibody Late 2008 and Early 2009 Hard Drive Replacement - iFixit Repair Guide
OWC SSD Upgrade Kits For MacBook Pro (2008 - 2009)
Even after 12 years, my late 2008 MacBook Pro hasn't given up. Upgraded it to 8GB of ram, added an SSD, and patched it with MacOS Catalina. Still use it everyday. :
Amazon.com: 2nd 2.5'' SATA HDD SSD Hard Drive Disk DVD CD ROM Optical SuperDrive Caddy Tray Adapter for Apple Unibody MacBook/MacBook Pro 13 15 17 Early mid Late 2008 2009 2010 2011 2012.etc : Electronics
1TB 500GB SSD Upgrade for A1342 A1181 A1260 A1286 2008 2009 Macbook Pro 13" 15" | eBay
Apple MacBook Pro 13" Late-2008 4GB Ram 500GB Samsung SSD Great To Upgrade READ | eBay
Installing SSD (Solid State Drive) in Your MacBook Pro 13" or 15" Unibody : 24 Steps (with Pictures) - Instructables