A mod I've been working on for a couple of weeks now in sketchup. Seems to be comming along pretty nicely. The basic model is almost finished.

Possibly going to replace the at-400.

UPDATE 18/8/10: Started work converting it into sa + added new screenshots.
UPDATE 23/8/10: It flies!
UPDATE 10/9/10: Completed.

In the meantime, you can download the modification from here: http://www.mediafire.com/?7e3oy15k8o9kof4