Even if trucks with a bonnet covering the engine in front of the cab are called 'Conventional' trucks in e.g. the USA, the truck with the engine placed under the cab/seat has always been an natural alternative (in fact the first truck in the world of 1896 was a truck of this type, with the driver´s seat placed over the engine).
Moving the engine, removing the bonnet
In the early 1930´s with increasing number of trucks using the fairly bad European roads of the day, the permitted axle pressures had to be rather limited due to the severe demands put on the road system. The problem of creating a more even axle load between the axles of a truck, with the engine placed over the front wheels and the cab behind the engine, helped the development of F-trucks, i.e. without a bonnet in front of the cab.
Volvo was interested in using this basic principle and as a result of this the LV75 was presented and introduced at the Amsterdam Motor Show in Holland early in 1933. The LV75 soon became a rather popular truck for special applications like garbage transport. Its most common use, however, was as a chassis used for light- to medium-duty buses in rural traffic.