Volvo was a fairly conservative company for a long time. That was not without reason. Since laboratory resources were limited in the old days, it was safer to continue using tried and reliable solutions, rather than trying to incorporate novelties which had perhaps not always been thoroughly tested.
This was completely in accordance with the honest principles set by the two founders Assar Gabrielsson and Gustaf Larson, who did not want 'the customers to have to act as test drivers'.
A well-tried truck...
A typical example of the conservative design of Volvo trucks in the old days was the L34. This medium-duty truck was a direct successor to the 'Sharpnose' trucks and was very similar (in fact nearly identical) in technical respects to the previous 'Sharpnose' L20 truck. As a result, the L34 was a well-tried truck, a fact which was most certainly popular with the customers (often firms like breweries and local delivery companies).
...but quite modern-looking
The exterior design was very modern, being very similar (but on a larger scale) to the famous PV444 car (and also to the PV83 taxicab). This Volvo design (which was probably influenced to a great extent by American cars of the era) became popular with the customers, and was of course quite modern-looking, with its headlights embedded in the fenders.