Can you help identify this part? (Braking System)

[nuts4coke]

This item is below my MASTER CYLINDER. I have four wheel drum (manual) in this 67 base coupe. My brake fluid looks like coffee, and the master cylinder has a nasty gooey substance sitting in the bowls. I'm replacing everything in the brake setup.... and I don't know what this part is. That larger item on the right side middle is some sort of electrical plug and the wire disappears into the firewall through a connector just right of this picture, which I believe is the dash brake light. There's no markings on it, and I want to replace it along with a new master cylinder and all the lines... I don't know if it's some sort of metering valve, or proportioning valve, or pressure regulator. I can't find a part that resembles it at many of the parts dealers, and what I do find that resembles it says it's for disc/disc, or disc/drum, and I need drum/drum.

Two lines from the master cylinder come down to it, then it has two front lines out, one for each side of the car, and then one slightly larger line to the rear...

Can anyone help with this, identify it, and then point me in the direction of a repro, or NOS replacement. Thanks...

[Mark]

Its called a distributor and switch assembly.  Its from the GM service parts manual section 4.874, and its the same part number for all 67 to 69 Camaros, 3904270.  Its the same as the original engineering part number shown in the AIM on page UPC4-A2 item number 6.

[nuts4coke]

Thanks Mark....

Any reason to think I should replace it based on the condition of the master cylinder, and if so, where can I find one?

[JohnZ]

If the system bleeds successfully, there's probably no reason to replace it. It's commonly called the "distribution block", although most of the vendors mis-identify it as a "proportioning valve"; it has no valving function at all. It just has a spool inside it that moves if the rear and front system pressure isn't the same, which grounds a circuit and lights the "Brake" warning light in the cluster. Most of the vendors have them, but they're not cheap.