I'm slightly confused...if you have an M6, is there a reason you want to install the pre facelift (pre LCI) kidney grill from the regular f06/f12/f13 (grand coupe`/vert/coupe)?
The color of the kidney slats and surround can vary based on what an owner wants to do with them in regards to colorization...but the original design of the kidney grill's differences are the number or type of slats. The early versions have 10 slats, the LCI has 9 slats, and the M models have 6 double slats.
The standard pre-LCI kidney grills for the non-M 6 series have
10 slats in each grill.
The LCI kidney grills for the non-m 6 series have
9 slats.
The M6 kidney grills have
6 double slats: