I put a rear sway bar in my 68 satellite. It's a frame hung unit from firm feel and sits above the axle. Works great.
68....How does it attach? My frame rails are stock but the springs are moved in about 3" per side and the tires come within 1/2" of the frame rails.
That would bolt up to the frame but would be 3" too wide (each side) for the spring mounts.