Brake Booster Blues

So the brakes on my 69 Dart have been getting harder and harder to stop the car. I thought I would check the diaphragm on the 50 year old booster and sure enough it presented zero resistance to vacuum. So I went to carid and found there version of what I needed and ordered it. Unfortunately when it arrived it didn't fit into the depression on the firewall. So a quick FABO search turned up a bunch of recommendations for Booster Dewey on the west coast. But when I contacted them Booster Dewey had sold the business to Booster Steve, who quoted me a price of $230 and said 5 weeks. With the summer fast running out, I found Power Steering and Brake Supply in California. Luis told me $150 and 10 days would get my booster rebuilt so off it went. Much to my surprise, 2 weeks later a beautifully rebuilt booster arrives at my door, and 2 days later its installed and working just like new.
Even better it solved a vacuum leak I didn't know I had and the car runs better too. Highly
recommend.

Yep, when the booster goes bad you get a vacuum leak every time you hit the brakes. My dad was pulling his hair out, replacing everything on an 5.0 EFI swapped 82 GT. It would surge badly because the EFI couldn't control the leak. I found it when he was driving it, everything was fine then he came to a stop with his foot on the brakes, as soon as he let off the Idle surge would stop. Press the brakes and surge again. New booster, surge gone.

Take a hand vacuum pump and pull a vacuum on the booster. If it won't hold, it's bad. They can leak at any time, w/ or w/o pedal pressure.