Unfortunately, CFS2 mdl files (which contain the 3D model) are incompatable with CFS3's m3d files. This means, with out the original model, you cannot convert CFS2 planes into CFS3. Plus CFS2 planes are not done in gmax and therefore cannot be converted into m3d files even after finding the original. However, there are people out there who have done some aircraft from CFS2 for CFS3. All original models and everything. Check out avhistory.org. They have a nice collection including a KI-47, F4U Corsair, and an F4F (FM-2) Wildcat.