Originally Posted by
HillRider
The only other time for this conversion I'm aware of was years ago by pro team mechanics whose teams were sponsored by Shimano. They wanted to use threadless forks and stems so they modified Shimano threaded headsets as you describe but only to keep their sponsor happy.
Here's one that was on ebay last month, no idea as to where it came from though, sold for GBP 41.00:
