Hi, how ya doing?

Are you looking to convert *.mdl files into *.bgl files? If so, go to the FS2004 Misc section and look for the Mercedes Benz or Porsche [beta version].
Pick the Porsche. It's scale is more accurate compared to the Mercedes. Both of them are my creations and I am in the process of making more.
You can use the *.mdl files within the addons for your scenery creation, but under one condition: Don't use any of it for commercial purposes.
And I am very close to creating the beta version for my Enzo Ferrari project.