I don't have Wings3D installed, but...........
add # in front of o Junkers_Ju-87B_Stuka_body and try again in Wings3D.
Add 1 to every face so 1720/1720/1720 becomes 1721/1721/1721 as an example.
Try this example file in Wings3D.
http://www.mediafire.com/?04zfl727v27y25g