Your ABS wil not even be involved unless you are braking hard enough to invoke it. When you do you will hear a rumble as well as fell a very rapid brake pulsation.
On some of the Contours, the rear brake pressure bias is controlled by pressure reducing valves in line where the steel brake line connects to the rear brakes hoses for each individual caliper. I wouldn't mess with them unless you like having the car swap ends on hard braking. When these valves act up, they cause that one caliper to not fully release. The valves are different between ABS and non-ABS and are not interchangable.
If you can find a shop that is willing to loan the gauges (if they have them, and they are expensive) you could read the rear brake caliper line pressure and find a like car to compare it with.
