Very common problem with Fords is sticking parking brake cables. That will cause the wheel to lock up on its own or when applying light brake pedal pressure.
Look where the cable comes out at the front of the outer casing near the front of the wheel. If a half inch or so of the cable is shiny, it hasn't fully released. Very often, if it isn't rusted tight yet, you can flex that casing and spring pressure will pull the cable back in. You can also try pushing the cable back in.
The best test is to remove the brake drum and check if both shoes are touching the large anchor pin at the top. If they are not, the parking brake cable is stuck partially applied.