68 full drum brakes. What would you look for first, hose,p/valve or master cylinder? I do not use e/brake. This happened al of a sudden.

Dave. First thing I would check is the rubber hose between the front-to-rear line and the rear axle. Might be a rubber piece acting as a valve inside the hose.

Rob

I had the same thing happen to me and the culprit was that rubber hose. The inside of it collapsed and the brakew wouldn't release. I couldn't tell until I got the hose off.

Loosen a rear bleeder screw to see if there is hydraulic pressure trapped. If there is not, then look for a mechanical problem.