I have never seen a "Buck"-fuse in such beautiful condition. The aluminum casewalls of an original are very, very thin and any ingress of moisture, especially over many years, oxidises the Al so that the structure crumbles to pieces. I have seen in my live only a very few originals. The screwthreaded bottom piece in these was made of a plastic material. This makes it undetectable (only the thin Al-case is metallic) by WW2 minedetectors. A brass-bottom-piece, like the one in the "E gun" photos makes a mine fitted with this detectable. In the originals that I have seen, the plastic-bottom-piece had, on it's upper circumference an about 1mm wide and 1mm deep halfcircle-shaped incision. The thin aluminum case was pressed into this halfcircle and so fixated the case to the bottom, so no horizontal movement was possible. I'm no expert. I have seen too few originals and no manufacturing literature at all to give an expert judgement. But, I would not pay any money for the offered empty hull. That's just my personal feeling.
Bellifortis.