The axle box comes in 3 parts: the casting, the brass, and the collar.
The casting is the main piece of the assembly:
The C-shape at the ends will receive the short and long wedges when the axle box is assembled into the frames.
The 3d view shows a recess at the top for oiling the axles. There are 2 holes that lead from this recess to the axle, but they’re not modeled yet.
The brass is the wearing surface of the axle box.
And the collar:
Here the axle box is assembled into the frame. The wedges are shown on either side of the axle box, and the pedestal cap closes the jaw at the bottom:
The wedges serve as a wearing surface for the axle box. They protect the pedestal legs.
This screenshot shows the long wedge. It forms a C-shape to cover the forward leg.
This shows the short wedge. It was a circular cutout at the bottom to receive a bolt head, which is used to adjust the wedge up and down on the aft pedestal leg.
The detail also shows the dimensions used (assumed).
And here the frames are laid side by side, ready for assembling the engine on top.
Here is the engine’s frames, starting with outlining and defining the dimensions:
This detail shows the intricate cutting around the jaw that will later receive the axle box assembly. I don’t think there will ever be the way to know what it actually looks like without disassembling the real #1.
And here is the “pedestal cap” that will close the jaws: