The M274 Mules were all powered by internal-combustion gasoline engines. The variants of the M274 with respective powerplants are listed below:
M274- 4 Cylinder Willys 4 Cycle ,M274A1- 4 Cylinder Willys 4 Cycle , M274A2-5 2 Cylinder Continental-Hercules 2 Cycle air cooled, variants M274A2 through M274A5
The manufacturers :
-M274 Willys-2,452 built 1956 to 1960
-M274-A1 Willys-1,905 built 1962 to 1964
-M274-A2 Bowen McLaughlin/York-3,609 built 1964 to 1967
-M274-A5* Baifield Industries-2,400 built 1965 to 1969
-M274-A5* Brunswick Corp. 874 of these were built from 1968 to 1970
Berliet GAK5 first series (1958)http://www.hoflandt-le-jardin-aux-oiseaux.fr/attachments/Image/Fiches_techniques_camions_grand_format/Berliet_GAK_5_1958.jpg
I think it's not a Horch. The front fenders of the Horch 830R looks different
Horch 830 :http://www.kfzderwehrmacht.de/Horch_830_Kubel_spat_WL-125662__Hoppe.jpg
Looks more like a Mercedes 170 VK :http://www.imcdb.org/i444454.jpg