It certainly looks as though the LMS diamond bogie is a copy of the classic American design (assuming the American one came first).
I have to admit, looking closer at the trucks on the model, they are not as bad as I had imagined and have some nice detailing.
Part of the issue is the thick layer of paint (like powder coating?) obscuring what is nice detail, but the main visual downer is the wheel profile.
The paint can be tidied to bring out better transom girder detail so I'm tempted to keep the truck frames - the wheels have
got to go.
The model is the 95T version as supplied to the Panama Canal project (which used 77 x 70T and 95T machines).
45T and 65T models were also made.
From one source a 45T G.A. drawing scaled off gives truck centres at 58"with 33" dia wheels.
The 95T model at 1/48 scales off as 72" axle centres and wheel treads at 33" (well, nearest the flange
).
From another source a G.A.blueprint of an unspecified model has axle centres 66", wheel dia. 33" - this might be from the 65T model then.
So looks like I need 4 x axles with 33" wheels with that lovely ribbing - I can add the heavier inside bosses which I guess are not present on standard freight bogie wheels?
The axle bearings measure 2.97mm so maybe nominal 3mm - which is not the 1/8" (3.175mm) I was expecting from an American model?