-Run IMG Tool (available at GTA3Files.com)
-Open the gta3.img file, which is located: [gta3 directory]\models\
-In the IMG Tool window, find and delete "dodo.dff"
-Add "dodo.dff" from this zip file (which is actually the Full-winged Dodo) to the gta3.img file, using IMG Tool.
-Run GTA3, and go to the airport where the dodo is, and it'll be full-winged!