WW1 GERMAN M18 HELMET - UNIT MKD - BELL L - FREIKORPS ?

Very interesting M18 helmet from the Great War / Inter War period.
Rare maker,known as the Bell L helmet as the factory symbol is a bell shape followed by " L " and ( size ) 64, this being the only size of shell made by this factory ( R. Lindenberg A.G., Remscheid-Hasten ).
The helmet has a brownish hue from the toned lacquer it was coated with , in my opinion during the Stahlhelm / Freikorps period inter war.
Post WW1 is was common to do this to give the helmet a parade type finish . Smooth paint, shiny finishes still continuing into the M35 period before the introduction of wartime matt Feld Grau.
The helmet has a number " 10 " painted to the front. This could be Regiment 10 from wartime or possibly a Freikorps unit .
I have forum posted the helmet for opinions on this but no one has a definitive answer although the helmet itself got the 100% thumbs up on authenticity.
The shell retains most of it's original finish and has the rounded ends to the air vents correct for this maker.
Stepped lugs.
Metal liner band with the strap fixings correct for M18 helmets.
Liner pads are the chromed leather type and in good shape with some service wear / sweat and 2 of the 6 tongue ends a/f.Leather is still supple . Draw string is original.
Rare " Carbine Clip " original chin strap and although shortened and with a repair is in good condition with the leather still supple. These on their own are expensive and near impossible to find.
Faint pencilled name / details to the rear skirt.
Cracking non Run of the Mill helmet, all original and in great shape for it's age and remarkably, still with it's chin strap.
If anyone has a take on the number to the front , please let me know.

Code: 55427