I'm glad everyone's brakes are so good. My truck doesn't have brakes that work right now. I'm looking forward to getting them working. Hydrovac parts are hard to find. Single circuit master cylinders allow complete brake failure with a single leak. Dual circuit master cylinders can still fail but they've been working out ok for the last 60 years. A 1.75 master cylinder would take a lot of pedal pressure if it didn't have 2,000 psi of hydraulic assist.
Crenwedge is sure right about the 2003 brake drums. The GMC/Isuzu was a WT5500 cabover with a Duramax 7800 six. I was away from home when the brakes went out so I took it to a shop. I just checked rear drum prices and it looks like I was ripped off big time.
