70-71 Dart Grill

A bit off topic, but anyone know why some of these grills have black fins and others painted silver like the outside? Were some only offered on certain models or years?

'70 had silver fins, '71 had black fins (the one pictured above is a '71). '71 demon sizzlers had the argent painted part of the grille colormatched to the exterior too for certain colors, could be yellow, red, etc.