The MN2 was fitted to pre war Triumphs, Douglas twins and post war Royal Enfield twins...The L suffix denotes 'long dynamo' which makes it post war so a Royal Enfield Twin such as the Meteor is the most likely candidate if the drive end cover looks like a 'normal' magdyno..
When fitted to the Douglas the body and drive end cover were a rather odd shape with pointed 'extensions' that protruded horizontally and gave the drive end of the unit an odd 'diamond' shaped appearance...Ian