Agree, probably white plastic around a steel rod core for the outer diameter and a horizontal bar with mid section bulge connecting the center to the cable drum.
Not familiar with the Malibu. If windshield, front deck, dash, and full cross seat with back rest cut down in the center, it probably had cable steering down each side. Otherwise it had both cables down one side.
You may not be interested in what I am about to say but here it is anyway:
Anchors for cable steering were in the transom on each side. Connected to the transom anchor was the cable with cable clamp. Cable was routed up through the front of the engine mounted lifting bracket with a removable cable adapter with a spring mounted removal pin.
Somewhere in the system were springs (one each side) that were set in tension when mounting the system, engine down on the transom...... reason being (opinion) was that the old 2 opposing cylinder (OMC) engines vibrated at low RPMs and the springs were to isolate the steering wheel from the vibration. They could be at the transom mounting point or the remote control adapter mounted on the front of the engine bracket as I mentioned above. Spring tension was set to 50% of length.
From the engine bracket adapter the cable went to a side mounted pulley just in front of the transom and another under the dash with the cable going from there to the steering drum.
On single sided mounting, both cables went to a pair of pulleys where there were single pulleys mentioned above, obviously one for coming and one for going cable movement. At the transom, there was an additional pulley on the opposite side of the boat to contain the cable on the other side of the engine for bi-directional steering, and then on to the engine bracket so that the engine could be directed in both directions.
Lone Star was a popular boat in my early boating days and some are still in service.....as you are attempting to do. Should be well worth your effort.