I have here a Valeo suspension control module for a Citroen XM with Hydractive suspension. There are several evolutions of this part through the car's manufacture so it is important to identify the one fitted to your car.
This is an early type Hydractive as fitted to series one cars and possibly series one and a half. The case is pressed metal painted black as opposed to later cast aluminium unpainted.

Case markings as follows:

Made in France
Suspension HYDRACTIVE ASC
73807802
12v 37-90 (Iam sure that refers to week 37 year 1990)
H2  (Possibly second version as I also have for sale version H4 and version H4.3)
S 2001