There's this tiny store in Littleton, CO that sells used manual camera gear and they had a few Pentax lenses that I picked up for $20-30 each (55mm 1.8 takumar and this 135mm f2.8).
Here are some photos of the lens.
The text reads: MC Auto CPC PHase 2 CCT 135mm 1:2.8 o55 336469
The front lens cover is original and the glass is super clean, the aperture (6 blades) is snappy and oil free. It also came with a 2x teleconverter by the same company. From what I can understand, the CCT means Closed-Circuit Television and, apparently, CPC developed these lenses for Pentax. The lens is very usable. Here are some test shots done at F2.8
Here's a 100 percent crop:
The last photo is it's closest focusing distance (1.5 feet). It says made in Japan and, other than that, I have no idea how rare this lens is or if it is only worth the $30 I paid for it. I did a search through the forums and didn't find much more about these lenses.
Let me know if you know anything about them! Thanks.