Lenovo ThinkPad T420s Hard Disk Drive Replacement - iFixit Repair Guide
My labour of love. Upgraded T420 with FHD screen + i7-3740QM CPU + AC 7260HMW WiFi/Bluetooth + 500 GB SSD + more : r/thinkpad
Amazon.com: Bfenown 2nd HDD SSD Hard Drive Caddy Tray Replacement for Lenovo Thinkpad T420 T430 T510 T520 T530 W510 W520 W530, Internal Laptop CD DVD ROM Optical Modular Bay to 2.5 Inch