Interesting, that is yet another variant to the 5 I knew of. Is that a genuine Citroen part or after-market?
Just check that your top heater hose has the clip-on fitting required by that thermostat, not the clamp fitting that some have. The diagram in the parts listing above shows a thermostat with a clamp fitting, not a clip fitting.
It also shows the temperature sensor in the other (horizontal) position, but that is not so important. There are actually 4 different positions for the temperature sensor on these stats, integral in the end of the housing, screw-in vertical through the bleed orifice, vertical clip-in in front of the bleed orifice, and horizontal clip-in from the front.