Cab marker lights are more often than not added not for their aesthetic appeal but because of federal regulations. The Federal Motor Vehicle Safety Standards (FMVSS) indicate that vehicles over 80 ...

As such, Chevrolet Silverado HD and GMC Sierra HD trucks in California cannot be equipped with the amber roof marker lights (RPO code U01), which are typically a $55 option.

The new design incorporates the three middle marker. Pacer Performance Products has a new addition to its Hi Five line of cab roof conversion light kits.

Have you ever noticed that some pickup trucks come standard with lights on their roofs? In fact, there is a safety reason for it, beyond the aesthetic appeal.