Second version, this one is the long one; 10x4 studs.
For this version, Body needs to be printed with support.
Wheels shaft is made by a 3mm nail cut at 47mm. Nail could be between 2.5mm to 3.2mm.
There are 2 wheel size for the shaft, it can be drilled if necessary.
Wheels need to be inserted with a press (here, a drill with an M6 screw on top).
Axis is first passed through the chassis, then the wheels are pressed in position.
The bigger STL file is the version with rounded studs, enables easier fit.
All the wagons of the serie I have designed share the same wheels.
Hook is just pressed in position.