Malcolm, Bob,
Thanks for the excellent input. Malcolm I have sent you a PM.
Bob, I didn't realise that they were available as repro, although I did look at a post-war BSA type muffler, which seems almost identical to the Chore horse exhaust.
Brian A. was able to help with the parts I needed for my Chore horse.....I just hope the boat carrying the package isn't hijacked by any pirates
Alex