Obusier de 155 mm Mle. 1950.
This good howitzer was the mainstay of the french, swiss, sweede, syria and moroccan towed artillery in the 60s and 70s.
The gun shown is depicted in the green olive drab of the French Army in that years.
Credits: Lot of thanks to Cplnew83 for the Berliet truck pictures, the green shade that I selected is from his Renault 2087 truck, and also for his useful indication about the camouflage schemes of the french military. Cheers.