The
MkIIIC's front diffuser air management differs in that instead of exhausting
the air out the side of the car as is typical, the air is exhausted out
the top of the sidepods either side of the cockpit. 
The
diffuser air exhausts into ducts located in the side pod. From the
duct the air empties out the top of the side pod. 
A
very visual example of the air flow separation and general untidiness of
the air that exits the front radiator duct. 