Actually, Ptrope built upon ALT1701's mesh, outright replacing something like 40 percent of the original geometry and then scratch building all his additions. And, hopefully anticipating one of your questions, ALT1701 is cool with what Ptrope has done with his model.
As for sharing it? Several of us 3D hobbyists have been askiing he do so before he suffers another disk crash. (I think he's experienced three since he started this project.)