I tried looking on here to, found some old posts that they interchange but thought there was newer posts that said they don't. I know the valves are different and some parts are the same, but when I don't know I'll ask here or stay with the belief that Ferguson knew what they were doing.
I guess now that you say it, I might as well tear mine down. I guess the thought was if my block is junk, I'm in a bad position of finding another where-as if I buy this one, I should have a good block. If I end up with 2, I should be able to sell it and get some of my money back.