My laptop was a T61p.
Sorry, I no longer have this laptop.
Last EFI for Capitan, Mojave and Catalina (serial deleted):
El Capitan is the last native system.
Mojave and Catalina only through Dosdude Mojave Patcher and Dosdude Catalina Patcher.
Dosdude Installer and Installer Post-Install work great with T61p / T61 (nvidia graphics are required).