I’m generally not into vintage parts. but this rear derailleur is pretty cool. It’s old school Dura Ace, pre-index. The unusual feature is the cage that can be opened to release the derailleur from the chain without tools (see pix after the jump). I have no desire to ever run friction shifters again, but I’d use this derailleur as the coolest single-speed chain tensioner ever. It’s a simple trick to run a shifter cable just from the barrel adjuster to the fixing bolt, without a shifter. Works great and you can even use the barrel adjuster to fine tube the chain on the single speed cog.