I found her back my beloved Thinkpad T61 : r/thinkpad
IBM Thinkpad T61 RAM Replacement - iFixit Repair Guide
T61 - Wiki
2GB Memory RAM Upgrade for the Lenovo Thinkpad R61 Series T60 Series T61 Series X60 Series and X61 Series Laptops (DDR2-667 PC2-5300 SODIMM) - Walmart.com
CMS B116 - Memoria RAM compatible con IBM Lenovo Thinkpad T61, T61P Ddr2 Pc5300 Sodimm de 8 GB : Electrónica - Amazon.com