Let's look around at some of the other areas of the truck for strokes and effects.
Although the bumper is old the chrome plating is still evident with a shiny reflective surface in some spots. I used a combination of cross-hatching and parallel strokes again. The top of the bumper was kept white to indicate reflection of the bright sky above. Parallel pen strokes done with a light weight pen can sometimes make the shaded area almost glow simulating the affect of secondary lighting. At least to my eye that is the case with the bumper.
The drawing is progressing as I fill in more detail on the remainder of the truck.