There was a Lionel socket for sale on here not long ago. Sold before I could buy it. At the moment I use the simple hex "spanner" with a mod of a slight bend to give clearance when malleting. I use a lump hammer in the garage. Never needed to use the lead one in the carry-kit. Grahite grease on the splines as per MMC instructions.
Re a Lionel socket....maybe a "group buy" if one could be copied by an engineer?