have filling the master brake cylinder daily but I can’t see any leaks around it. Truck as close to 200,000 miles
OK , the fluid is going somewhere but no one on the web can see the leak. So just put this in the shop before you crash in to someone.
If you don’t see any leaks anywhere, my guess is the master cylinder is leaking into the booster.
If you disconnect the MC from the booster, you can pull it away a little bit even with the pipes connected. See if there’s fluid coming out the back of the MC or pooled up in that area.