In the book 'Stanguellini - Big Little Racing Cars' by Luigi Orsini & Franco Zagari there's a drawing on page 319 showing the arrangement as applied to the 750 Sport Internazionale (not an FJ).
The cables are to the rear of the axle and attach to the axle at the coil-over damper mounts (also located behind the axle tubes).
The lower chassis rails pass under the axle. Brackets on the rails (also to the rear of the axle) stand up to about the height of the axle. The cables attach to these brackets and the offset from the chassis rail is possibly sufficient to create a torque tube effect.
With the cables at the same height as the axle when at rest, any movement of the axle up or down would increase the tension in the cables and try to pull the tops of the brackets inboard.
The caption for the drawing says the cables were adjustable.
Edited by MalcolmC, 20 October 2019 - 20:35.