Often a model and serial number from your equipment is all we need to identify your engine.
Some engine manufactures provide additional numbers to speed up and verify your engine ID.
In the case of Cummins those numbers are the CPL and serial numbers on the engine ID tag.
On Cummins engines such as the 3.9, 5.9, and 4.5 the engine ID tag will be on the side of the timing gear case near the injection pump.
The CPL and serial numbers will be in these location on the tag.
Other engines such as the QSB3.3 and similar engines the ID tag will be on the block toward the rear.
The serial number will be located here. The CPL field on these engines can be left blank like on this tag.