[se5a]

you can actualy open a .x file with a text editor such as notebook. it's all just a bunch of coordinates. inside the .x file the texture file is called, there is no requirement for it to be any specific size. the larger .x files probibly mean that the shipset has a higher poly count. if the textures are bigger then the texture detail will be better. the higher these two are, the better the ships tend to look, but the more work the computer has to do.

DG's idea should work for the texture files, with the portrate files you may have to keep them the same size. (you can easly see which is a texture file in most shipsets by looking at it - texture files look like someone has peeled the ship like an orange.)