I installed a set of adjustable rear lower control arm in my 86 Mustang open track car.  I wanted to lower the rear of the car by about an inch.  I debated just cutting the spring, and didn't want to go with coil-overs at this time. And eventually I will be installing a torque arm, so it had to be compatible with the new lower arms.

    I chose a set of Maximum Motorsport adjustable spring perch lower control arms.  One urethane bushing at the box end, and a metal heim style bushing at the axle end.  It came with provisions for the sway bar, which I wanted.

    I was able to adjust 1 inch out of the rear ride height.  Not bad.

Drivers side.  You can see the perch and the adjustment screw.
Passenger side
Passenger side.  And you can see the blown out lower seam on the DynoMax muffler.
Drivers side