Materials of the author «SPINTIRES HARDCORE» 3

MeshConvert - a mesh editor for the Spintires format (those in MeshCache or _m)
MeshConvert saves ST game meshes for different game versions.
But not all meshes can be converted correctly; it is preferable to use the original X-meshes (with the .x file extension).
Also, MeshConvert can be used to edit the mesh XML.

Usage:
With this program, you can convert vehicles from the 03.03.16 version, specifically cached mesh files, to MudRunner.
Important! Don’t forget to then distribute all texture and model files into the necessary folders (which should be created beforehand): meshes go into the _m folder, and textures into the _t folder, accordingly. And provided the vehicle config in classes/trucks is correct, taking into account the new requirements for wheels and steering response. Also, the correct config for the wheels themselves in classes/wheels. The vehicle will appear in the game, though without drive shafts, as mentioned by the user above. Difficult? Possibly for some. But those familiar with the subject will figure it out.
How to use: unpack the downloaded executable into any folder. Double-click it, and in the window that appears, at the very bottom above the Load and Save buttons, select the path to the desired model (vehicle, addon), open the mesh, then click Load, and after that Save. A file with the _converted suffix will appear next to the model in the folder. This will be the finished mesh. Delete the old one, remove the suffix from the filename. That’s it.
Thanks for the instructions: Denis Korolev.

Source: SPINTIRES HARDCORE group

Map editor with the ability to convert maps to the new version of the game MudRunner 18/03/06.
If the map does not open after conversion, you need to reselect all the vehicles.

Tested on "Blackwater Canyon" - everything works.
The archive contains two versions: 32-bit and 64-bit.

LevelTools - another map editor from third-party developers.
Allows you to restore prebuild files, but not completely; you can edit maps in Spintires Editor, Spintires Mudrunner - Editor Beta, and you can also merge maps.
No need to recreate terrain.
In the settings, the path to the levels folder must be specified manually.

The archive contains two versions: 32-bit and 64-bit.