A bound neck with "G-shield" headstock, ebony fret board, and diamond fret board inlays would not be standard for a D-25. If it was a custom or special order, it would likely indicate that on the label. It's possible that the neck has been replaced or modified. It might help if you posted some pictures. You might also contact member Hans Moust (send him pics and the SN) through his website, and see what he thinks.