Douglas started making industrial trucks as a sideline in 1928, and it continued after the war. Railway freight, automotive factories, and the post office were all customers. Some had road registration plates to make them legal for short distances; top speed limited over the road practicality! There were a number of configurations; high lift, low lift, tractor, crane, mechanical lift and on the last models (I believe) hydraulic lift. The industrial truck line was sold to Douglas dealer Eddie Withers shortly before the Douglas factory was sold to Westinghouse.
This advert dates to about 1943.

-Doug
[fix typos. 05May16 -Doug]