I take it when you say original you mean the midland type?
I've not had any dealings with a rebuilder so I'll suggest calling Hill's or Casco and ask them. They may do them in-house or send them out, but I'm sure they'll help you.I have a 1956 Original brake booster for my T- Bird that I would like to install but I do not know if it is good or not. Can someone out there recommend I good firm that rebuilds these units ? Thanks Tom