Yes, high backs look the part in a later model A car for sure as well as a later B-car. For some reason the low back Bostroms look as cheap as the factory intended for those cars to look back then. they were both experimenting and discovering at the time.
By the time the A-cars came to be in the game, advancements had been made in seat comfort and looks as well as safety.

WOW, NOS A-100's? Those bases were to keep the driver up and high in those vans/trucks I guess.