'98 F-150 XL 4.6 auto. Some time the right rear brake don't release. Very often the same wheel locks up. Mostly cold, but also after driven. All flexable lines have been replaced, new brake cylinders, new shoes, turned drums, replaced all hardware in rear brakes, checked parking brakes for proper operation. Blead system each time any work was done. When the brake locks, the anti-lock system works correctly. One thing I found different is the rear differential does not have a sensor or wiring for it, maybe picking up signal from speedometer. Any help, Johnnyd