That has travelled a good distance from Oldham UK if you've picked it up in the USA. Can you post a pic or 2 so we can see which one you have. I've posted some information in the past here
https://allmetalshaping.com/showthread.php?t=21151 . Unfortunately the forum doesn't seem to like short search terms like 'DFS' making it hard to find other information here but I saw one other thread by a guy here in the UK that had bought an older cast frame DFS shrinker.