Sorry, I just caught the question "can this be changed to .MDL" my answer is, yes it can, but you first need to export a .OBJ from the tool, then bring it into another 3d tool to save out as a .MDL it can definitly be done! I wouldn't bring the high-res (HI) models into 3DGS though, because those are really meant for normal mapping onto low poly walls, creatures etc. but (MED) or (LO) model settings would probably work just fine!