Propulseur 2 galets

Which Kégresse is this?

This picture is found in Citropassion n° 1 (april 2003) in an article about Pierre Terrasson, a man who worked for Citroën in Montlhéry (test laboratory) in the thirties.

The truck in this picture seems to be a P107 by the big front wheel, but the system is unusual with only 2 big rollers and a triangular plate in the middle.

Dowload the leaflet by Pascal Honneger about the Kégresse with 2 galets