Mine started leaking awhile back, as of now from sitting 4 months the rear reservoir is pretty much empty. Looking to replace with something preferably aluminum. I don't really need a $300 Wilwood unit just something from the local parts store that will bolt on. If I need to re-flare the ends for metric that's fine. The current one is from manual disc brake Granada.
Gary, On my Fairmont, I am using a factory aluminum manual brake master cylinder, from an early FOX 4 cylinder, manual brake Mustang or Capri. Looks pretty much like the same master cylinder as your 70 Boss 429 Mustang, and likely just like your current Granada unit. You may need to find one from a donor car at a wrecking yard, as I believe the aftermarket replacements are cast iron. Many guys also have been using an aluminum and plastic master cylinder that was originally used on Late 80ish-90s MoPars. Similar versions are sold thru performance aftermarket brake companies.
I did a bit of research Rory. Dorman M39567, application is a manual brake late 80's Ranger, Bronco II is a direct bolt-in to most Fords of the 60's 70's. It's modern looking with the roundish body, plastic reservoir, aluminum. I'll have to reroute a couple brake lines, so no big deal.