Guys, on my '86 IROC Z, the slide piston inside the proportioning valve has leaky seals on it, which allows a small leak to exist on the vent, which is built into the end cap. I would just replace the whole valve assembly, but they don't make it anymore. I could use a couple year newer valve but they changed the line flare fitting thread pitch from standard to metric, after the year model I have, so that approach would require me to cut and reflare all the lines with new fittings. I have found a few on Ebay used for around 50 bucks, but who knows what shape the seals on a used one would be like.

So based on this info I'd rather find a seal kit and just reseal the slide piston inside the valve I have and be good to go, but I'm not having any luck with finding a reseal kit for it. I know brake fluid takes a different type of seals than petroleum, wonder if I would be able to just size up the correct seals at a parts store. Any of you been in this jam before and if so, which way did you go to remedy it?