How do you remove a (rear) bumper cover from a 1991 Loyale wagon?    Are older bumper covers from DL's and GL's compatible to the Loyales?   

There are screws on the bottom.   They are very tight, even if not rusted.

It takes a LOT of pressure on a screwdriver that fits the cross in the screw well to get them to turn.   And vise grips clamped to the shaft of the screw driver.  I used part of the car's weight for the force to keep the bit engaged.