French pump appliances of this era were designed to include a very large crew cab for between eight and eleven crew members. Without a water tank, the rather limited locker space was actually quite adequate, especially as most hose was carried on the two hose carts hung on the rear of the truck...Modern FPT have around 3000 litres of water on board and are designed for either six or eight crew, depending on individual SDIS preference. Pumps without water tanks have long since disappeared but did remain in use into the 1980s!
This earlier design was intended to be second due at a fire, or even third behind the TTL, with a PS or FPT going in first, as these had on board tanks.
The truck next to the Citroen is a contemporary Berliet GAK, similar to the example more fully portrayed in oicturre #18901. Both of these brands - along with many other French ones - are now long gone, with Renault RVI the sole survivor. In the 1970s French fire services operated many makes, including Saviem and Unic as well as a lot of GMC and Dodge units inherited from the US forces after WWII and kept in service for decades.
Jacques Peter's picture 42444 on this site has a front view of the Berliet GAK next to this Citroen, as well as a little background information about Berliet fire trucks.
This earlier design was intended to be second due at a fire, or even third behind the TTL, with a PS or FPT going in first, as these had on board tanks.
Added by Rob Johnson on 16 March 2021.