Spectraflame bright red and brick red
 
Difference between bright red Spectraflame and brick red Spectraflame.  These Fire Chief Cruisers are examples of both shades of red.  The car on the left is painted dark (brick) red, while the car on the right is painted bright red.  Bright red was used primarily from 1968-1970, while brick red was used in 1971 and 1972.  Bright red is very transparent.  Brick red is thicker and more opaque.