For this you can use tool called BBAC:
https://forum.yoyogames.com/index.p...import-of-models-into-your-3d-projects.60628/
Just launch it, create a new project, hit the file, select import mesh and load your d3d file,
now you have the mesh in the content browser, so you can put it into the scene, if the mesh is not visible reimport the mesh and uncheck "keep vertex colours" (also would be good to import the texture and check if it fits correctly if not you can reimport it again with flipped UV coordinates), once you have that done, just select the mesh in the scene, hit the file again and export it to your desired format. And that's it, hope that helps!