8 years, I got the proportion valve off a 73 bonneville
It is a cast iron. I put some disks on front and 9" rear 3.70, ford master cylinder. worked for years. 1940 coupe (pictures) on profile. I had a 305 with saginaw overdrive. Now, I have a 500 cadillac with TH400 and beefed up the MMII, boxes. As orginal as I can inside and out.
I had to replace the ford master to a corvette master. The front was working fine, until when I rolled on a rack to alignment, it was raining that day and I was scared becaused the man working on it. So I went very slowly, the rear was wanting to go (I realized no brakes). The guy working on it, I had the front disks wanted to stop (ECI) 5/1/2" for the 40 16" originals all around.
The master seemed to work. The rear would with a fight just to get hydraulic to the rearend. I stomped on the brakes, it is manual. that's my Footstomper name.
A friend told me to go to the junkyard, we have snow, so I got in the garage and pulled the proportion valve last night. I cleaned it as the best I could, I used some air through orfications. The rear side had a fitting and on the front side had a pin, I did tapped alittle. The rear side came out pipe brass with a "O" ring. I got a allen wrench and wd-40, I cleaned it and air began moving. I put all the lines (about all the bonneville had, at least 6 lines). It was cold, and I will have to try it today. I have the car up on stands, and when someone to look at the right tire whether if it stops (I hope), if it keeps rolling with make me mad!