Did Caterham/Arch notch the chassis, or was that a modification made once kits reached the US? My recollection is that some of the first, if not the first, Zetec’s were installed in US cars.
The lack of a body patch on the right side to cover where the Zetec exhaust would have been confirms to me that this always had a Duratec.
Believe the early Duratec cars had the notched left rear fender as that was all Caterham made at that time.
This may be a one of one Seven, with the combination of clam shells, Duratec, red interior, wagon wheels, and white piping on the tonneau cover.