Saurer AG based in Arbon, Switzerland was a manufacturer of trucks and buses under the Saurer and Berna (beginning in 1929) brand names, active between 1903 and 1982. Their vehicles were widely used across mainland Europe, particularly in the interwar period.
When purchasing a new truck from Saurer one got this Omega for free.
My 1944 Military 30T2 has a plain outer back cover, but with the correct markings on its inner face. Really enjoy wearing it once a week, (mainly as a break from my 3570.50 and IWC Portuguese Chronograph).