Lenovo ThinkPad T420 i7 3.5GHz nVIDIA 16GB 1TB SSD, 2TB HDD Windows 7 10 or 11 - LBH Insurance, Inc.
NeweggBusiness - 2nd HDD SSD Hard Drive Caddy for Lenovo Thinkpad T420 T430 T510 T520 T530 W510 W520 W530
ThinkPad T420 Hard Drive Replacement - iFixit Repair Guide
I got free Lenovo T420 i put there Sata SSD 250Gb [Win 10 activated with original key for Win 7] i clean it and ive done little cooling mod [Temps drop -20C
2nd HDD SSD Hard Drive Caddy for Lenovo Thinkpad T420 T430 T510 T520 T530 W510 W520 W530, Laptop CD/DVD-ROM Optical Modular Bay - AliExpress