[68gmsee]

bossrod,

New recruit here. I was reading the different posts and happened to see yours with the brake problems. Did you find out what caused it?

I had the same thing happen to my 69 some years back and after spending a whole weekend checking everything I could think of, I found out that the rubber brake line on top of the differential where it goes to the frame was the culprit. It had swelled up internally that it was allowing "pressurized" fluid to the brake drums but was not allowing it to go back causing the rear drums to lock up.