This Fross-Büssing lorry is most probably a Fross-Büssing type 4000. By order of the OKH, 200 exemplars were manufactured in 1940. They were ordered as horse transporters but were actually used as normal lorries.
This Fross-Büssing type 4000 was used as field kitchen lorry. The photo was made in Wilhelmshaven in March 1941.