I recently bought a Zone RV and needed to raise the Tow-bar tongue by approx 100mm. For flexibility I wanted it adjustable and Allin engineering (Giorgia: Allin Towbars Admin <admin@allintowbars.com.au>) were able to design a new shaft (see images) that would be able to do the job. My first trip will be to Cape York so it's going to be fully tested! Thank John Canny for the heads-up!