I “think” you enjoy this… T61 (256 Gb SSD Debian 10, RAM 4 Gb) and E14 2021 (upgrade with RAM 16 Gb, 1 Tb M.2 for Windows 11 and 256 Gb SSD for Debian 11, all Crucial) : r/thinkpad
Hard disk shelf is designed for Lenovo IBM T60 T61 T40 T41 T42 T43 optical drive bay sataiii supports SSD hard disk shelf - Price history & Review | AliExpress Seller -
9.5mm SATA 2nd SSD HDD Caddy For Thinkpad T40 T41 T42 T43 T60 T61 T60P T61P Z60 Z61 Hard Disk Drive Caddy - Price history & Review | AliExpress Seller - Azazel
Lenovo ThinkPad T61 SSD boot test w/ Windows 10 64-bit - YouTube