dsc69887.jpg

Flash shot of the engine's ID plate. This ID plate is just barely visible in dsc69875.jpg, located on the mounting bracket at approximately the 10:00 position.

The ID plate reads

Rocket Engine
Part Name: Rocket Engine Assy Ascent Lunar Module
Contract No.: NAS9-7498
Part No.: RS000580M
Spec No.: [blank]
Stock No.: [blank]
Serial No.: NONE
Model No.: RS1801C
Accepted: [blank]
Weight: 172
Insp: [some sort of inspection stamp]

Yes, the engine's serial number is the word "NONE".