Engine serial number and chassis serial number.

The engine number is on the block. It will start with the engine model # (110, 117, 115, 130, etc.,) followed a subtype (920, 320, etc. not real numbers, just made up) and THEN the serial number.

Example (not real, just for explanation)

110-920-0123456

This is the M110 engine,(110) low compression US version with secondary external mounts for the "S" chassis, (920) and then the engine serial number (0123456).