Well, it doesn't seem to fit into any one category nicely. It's most similar to a PT3080 but it's glossy black and not silver.

It has the serial number on the top ring and not on the side.

It has an triangle instead of a dot for aperture indicator

The numbers on bottom seem engraved and not just printed. and distance numbers seem slightly bigger

So what do I actually have here? a Franken-lens that someone hacked together from other lenses or some small run factory demo/test lens? The lens is really nice to behold.. the black glossy paint is very shiny and looks great.. it's one of the favorites in my collection.
--mike