Hi Dr B, Many years ago I did a survey on which cars had the grey headlight covers. Here is what I found, as posted to my 914 Can Am website:
https://bowlsby.net/914/CanAm/"Coincidentally overlapping with the 914 Porsche Limited Edition production time frame, during Spring of 1974, Porsche 914 cars were delivered with light grey headlight relay covers in the front trunk. A survey of Spring 1974 Porsche 914 cars, indicates that from March through at least part of May, all 914 Porsche cars were manufactured with the light grey covers. While not an exclusive feature to just the 914 LE cars, if the covers are original, it is another indication of the authenticity of a 914 LE car, and period-correct covers!"