CMS 8GB (2X4GB) DDR2 5300 667MHZ Non ECC SODIMM Memory Ram Upgrade Compatible with IBM Lenovo® Thinkpad T61, T61P Ddr2 Pc5300 Sodimm - B116 at Amazon.com
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
T61 - Wiki
CMS 8GB (2X4GB) DDR2 5300 667MHZ Non ECC SODIMM Memory Ram Upgrade Compatible with IBM Lenovo® Thinkpad T61, T61P Ddr2 Pc5300 Sodimm - B116 at Amazon.com
8GB (2x4GB) MEMORY RAM FOR IBM Lenovo ThinkPad T61, T61p DDR2 A41 | eBay
IBM Thinkpad T61 RAM Replacement - iFixit Repair Guide