Finding the engine number on LX and LW engines

The number of your Gardner engine is stamped on the crankcase at the front, close to injector pump return spring. The example below features an LW engine, but the other models are the same.

You may have to clean that area with a wire brush.  The number will definitely be there.

Once you have the serial number of your Gardner you may be able to establish its age and other details by contacting: http://www.enginemuseum.org