If you only need the outer ring, Yashica DSB and YUS (single coating) lenses can be found for a very low price and swapping them looks to be quite simple.
BTW, the YUS 135mm f/2.8 is really a nice compact lens if you run across one.
If you only need the outer ring, Yashica DSB and YUS (single coating) lenses can be found for a very low price and swapping them looks to be quite simple.
A year or two back there were some new Yashica ML lenses on ebay going cheap. They seem to have been a batch intended for CCTV and lacked stop down pins. I haven't got round to replacing the pin because I use it exclusively for video and stop down manually, but I checked out mount removal and it looks very straight forward, so I agree - use a cheap donor DSB for the job.