Known as Silversides because of the way the bus sides looked, they were constructed by General Motors (GM) who made about 2000 of them starting from 1947. 

These buses were employed as Greyhound buses to transport people across cities in America.

They came in 2 versions, a larger 41 passenger seat configuration called PD4151 and a smaller PD3151 with 37 seats. In both the prominent feature were - fluted aluminium side panels.