I have access to a local craftsman who fabricates custom made lowering brackets for the Fiat 600 and Fiat 850 cars. In the attached picture, it shows how the bracket attaches to the spindle and leaf spring. These brackets fit perfectly as they are built directly on the spindles. This method lowers the car approximately 1 1/2 inches. A set is currently installed on my Fiat 850 Sedan and the fit/tolerances are amazing. You can also adjust the camber of your car which is especially helpful for lowered cars or race cars. The price is $350 a set plus shipping. A set of these lowering brackets are available in Europe for 420 euros or $458 plus shipping to the USA!
We have one set for the Fiat 850 available, but other sets can be made to order, including the Fiat 600 version. If you are interested or have questions, please email, text or call me. Thanks. Bill