The directory OBJ_MTL contains the OBJ with MTL and TGA files.
The OBJ contains the Collision Mesh too. Material collision.tga
The directory SOURCEENGINE contains the compiles valve object.
The model is compiled using HL2DM. It could be used in any
other game, based on HL2DM engine and up.
Copy the materials and models into your gaming folder. ie:
<STEAM>\SteamApps\common\Half-Life 2 Deathmatch\hl2mp
The model appear named : mlp/applejackapplewagon
In gaming you can include it as an prop_physics.
It does contain the collision model.
For SFM place the Object "Center" to the Ponies-"Center"
and rotate the Wagon until the wheels on the floor
You can control the cage and the wheels with Rotate