The 450SLC 5.0/500SLC coupes were produced by Mercedes-Benz from 1978 to 1981 and are the rarest post-war models ever produced by Mercedes Benz. They were manufactured by Mercedes Benz to homologate the 450SLC for road rally purposes. Some cars were campaigned with factory support, but the rest of the production was sold to the European market to meet homologation guidelines.
The cars differed from the stock 450SLC’s in several ways. The hood and trunk lids were made from aluminum for significant weight savings. The cars also had front and rear spoilers from the factory that resulted in a 9 —10% reduction in wind resistance and a higher top speed. Top speed exceeded 142 mph. The motor was amoung the first aluminum V-8 production motors produced by Mercedes-Benz. It was lighter than the 4.5 liter iron block counterpart and produced over 300 HP in SAE HP.
The chassis numbers for the 450SLC cars started with 107026 and the motor numbers started with 117960 indicating the 5.0 aluminum block motor. The combination of the rigid chassis, lighter weight and higher horsepower made for a quick, reliable and competitive car that won or placed in several international road rally events, such as the Paris to Dakar and Mexican Road Rally events.
Source text & picture 2: http://www.mercedesheritage.com
Source for picture nr 1. : http://www.autobild.de