I retired from working at TMMK powetrain department and used to put these labels on the engines as part of my work. These labels also identify engines by different trim and transmission for inventory control and sequence with the body assembly plant
The barcode on the valve cover gives you the date and time your engine was assembled at the TMMAL My engine was assembled on April 12 @ 10:19 pm Knowing this date could be helpful in any recall or problem because they can traced the engine history and confirm any assembly or machining...