1983 was something of a transitional year for IMSA. "Silhouette"-type cars like the Moretti/van der Merwe Porsche 935 in the foreground were on the wane, outclassed by pure prototypes like the March 83G. Porsche, however, wouldn't have an IMSA-spec prototype until the 962 arrived in 1984, so customers like Gianpiero Moretti had to either soldier on with the obsolete 935, or build Porsche-powered Lolas and Marches.