Diagram reference number 3 in the image below:
" Fitment: 2006 TOYOTA TUNDRA - 2 door

Application Notes: O-Ring

Category: Cooling

SubCategory: Radiators, Coolers and Related Components

Position: General

Part Number: 9020125007


This is a Engine Oil Cooler Gasket that fits the 2006 TOYOTA TUNDRA - 2 door with the 1GRFE engine. The Engine Oil Cooler Gasket is designed by TOYOTA to be part of the Cooling-Radiators, Coolers and Related Components. The Engine Oil Cooler Gasket has a position on the vehicle of General. The 2006 TOYOTA TUNDRA Engine Oil Cooler Gasket is a factory made TOYOTA OEM part and it comes with a 12 month 12,000 mile warranty (parts only). Do not be fooled by an aftermarket TOYOTA TUNDRA Engine Oil Cooler Gasket! Buy a factory TOYOTA part and receive peace of mind!
This factory part has a part number of 9020125007.