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) at Amazon.com
CMS 8GB (2X4GB) DDR3 8500 1066MHZ Non ECC SODIMM Memory Ram Upgrade Compatible with Lenovo® Thinkpad T400 2764, 2765, 2766, 2767, 2768 - A35 at Amazon.com
ThinkPad R61 Model Name: 8943DLG Part Number: UV1DLxx ...
IBM Thinkpad T61 RAM Replacement - iFixit Repair Guide