If you look at the right-rear quarter shot, you can see "SERA" on the base of the right tail fin. SERA is or was a wind tunnel in France (near Paris?) that, among other companies, Porsche used to refine designs for a number of their race car bodies. One of the later iterations of the 917LH (langheck, "long tail") was sometimes referred to as the "SERA body".
Been re-reading "Excellence was Expected" recently.
-soD