See Figure 1, 2 and 3
The engine serial number is located on the right rear of the block at the cylinder head contact surface. The prefix will be L24, L26 or L28, depending on the engine displacement, and the three-digit (1970-73), four-digit (1974) or six-digit (1975-83) serial number will appear next to it.
See Figure 4, 5, 6 and 7
The engine serial number is located on the right rear of the block below the cylinder head. The prefix will be VG30 (which designates the V6 engine), followed by a five-digit serial number.