We can guess though not know.
Waiting for the old tooling and production line to wear out before replacing.
Felt truck buyers were old fashioned, conservative, not accept change well. Thus lose sales.
Keep Chevrolet behind the times so there would be a real reason to step up to the other GM divisions and justify spending more money for a Pontiac, Olds, Buick, GMC.
Preferred to reinvest profits in other ways/divisions. Jeffrey
All good theories.
Perhaps the war slowed product development. Or maybe the war left Chevrolet with a surplus of 216s to sell through after the war, thereby reducing their motivation to move on to a full-pressure design.
Whatever GM's reasons were, the 216 surely stood the test of time pretty well, in spite of its limitations. I'm amazed at the countless stories here of them being revived after 30-50 year naps.
