Each engine is referred to by both its family designation, such as 1GR-FE, and its production or serial number. The serial number can be important when ordering parts. Certain changes may have been made during production of the engine; different parts will be required if the engine was assembled before or after the change date. Generally, parts stores and dealers list this data in their catalogs, so have the engine number handy when you go. Refer to the illustrations to determine the engine number location.