Little pit stop tractor - dumper

Wanted something to put behind the awesome little pit stop tractor created by @rorys3D and the great window version remixed by @Corbin1747. So I created this little dumper that you can hook behind the tractor.
It's a two part print whose parts snap together with a little snapfit mechanism. For the tires, just use two screws and two small tires from the little pit stop tractor.

Print instructions for the top part:

• position it with the opening at the top (default position in .stl file)
• enable supports (for the wheel house and rail cutouts)

Print instructions for the bottom part:

• lay the object on its side (default position in .stl file)
• enable supports (for the rails and the connector)

I have also added the STEP file if someone wants to improve on the design or maybe add another top part.