Whodunnit??

Not enough photos.  You at least need a shot of the boiler and tender.  It does look like an import.

To me the drive train components and the underside assembly elements look to me scatch built work.   I can see no markings on the gearbox.     Perhaps a closeup migh help.    It might be a Central Locomotive Works (CLW) gearbox, but they never did a mohawk that I know of.    Also no importer that I know of soldered the ashpans on the loco.

A note I think I read once commented that the early brass was always imported in pieces.   This was done so they could be sold as parts or kits or somesuch to avoid higher tariffs.    Apparently the tariffs on the uit in pieces were lower than assembled locos.

So all the brass from the 50s-60s-70s were brought in as "kits".    The chassis was assembled with the motor and all the valve gear.    Generally the trailing and leading truck were not installed.    ON the "better" Max Grey and US Hobbies for example, the ashpans were not installed.     The motors were too big to fit into the boiler, so you put the chassis in and mounted iwth 3 screws, one in the cyclinder saddle, and two on the cab back, and then used 4 small screws to attach the ashpans.

Since that was a common practice it is also a clue that this loco was proabalby not an imported brass model.

I have attached more images:

-The FWH is different, and the L-4 is slightly longer

-A comparison of the Sandbox vs my USH NYC L-4B.  Note sandbox covers are different. The qty of safety valves is different.

-The tops of the cabs of the engine vs my L-4B.  Note the difference in the wind deflector vs the USH engine.

-Another top of cab shot.  Note the engine is slightly shorter than my USH engine and the cab roof has no rivet detail.

-The turret comparing both engines. Note the difference in detail.

-The water deck of the tender vs. my L-4B.  (The overflow cistern has been removed (correct!) but note the difference in the hatch cover and its location on the water deck vs. the L-4.

-An image of the rear tender sheet.  Location of capacities and location of the ladder are incorrect.  (NYC tender ladders were all on the engineer's side of the locomotive.)

-Image of drivers and rods.  The rods are unlike the USH engine.  Drivers may be correct but can't compare since the USH L-4B has Scullin drivers.

Comments?

All of my USH, Westside, and PSC engines were obtained in kit form, with the boiler one assembly, and the cylinders, valve gear, and running gear with motor as the second assembly.  You are correct that three screws were used to assemble the two parts, the front truck king pin and two screws in the back under the cab.  The tender was already assembled and included as the third piece.  There were bags of parts such as running board steps, etc. added after the two assemblies were assembled.

So what about an early Japanese custom model?  I think there were a number of relatively good “one offs” out of Tokyo for servicemen stationed there.  I think that’s how Max Gray got the idea.