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
How to replace fan in Lenovo ThinkPad T61 – Inside my laptop
XY tech - ThinkPad T70 in a T61 shell, i7-7820HQ, 32GB RAM, dual M.2 + dual SATA3 gives it plenty of storage. An LED modded QXGA (2048*1536) display rivals modern laptops display
IBM Thinkpad T61 RAM Replacement - iFixit Repair Guide