Actually, it's the third generation OV15. But yes, the "L" designation never existed. Not in trade publications, catalogs, packaging, or spec labels inside the lights, never.
Yeah besides this version of the OV-15, there's the most common 2nd generation which is what most would consider a "normal" OV-15 and there's the mid-60s version with the external bolts on one side where the slipfitter is. I think that version may have had a pushed-forward PC socket like the Canadian Cooper OV-15s.