Well, you have what is called double action brakes on the rear of a Ranger. Since most stopping is done going forward, the brakes are built to stop better in that direction.
When stopping the front shoe is pressed into the drum (the short shoe). This caused it to rotate away from the anchor pin (at the top). This rotation, pushes the rear shoe into brake drum since it cannot rotate because of the anchor pin. This is what creates the stop. In fact, in very old plymouths the wheel cylinder only had one pin and it pushed on the front shoe. Those things would hardly stop at all going backwards.
So, if it is dragging in only one direction, you have something put together wrong. Something that is allowing one of the shoes (probably the front shoe) to move away from the anchor pin without hyd pressure being applied.
Drum brakes are designed to have a small amount of pressure applied to the wheel cylinders at all times. That is to keep the cups expanded against the sides of the cyl and not suck air into the system.
If the front shoe spring was soft (or installed wrong) and it moved into the drum it would drag a lot more when to turned the wheel in the forward direction. And stop dragging in the other direction since the wheel motion going backward pulls the shoes away from the drums.