Dark chocolate brown was used in 68-69 with cars that came with saddle tan or nugget gold seats and interior panels.
Of the multiple carpets available out there these are the best. These are correctly molded to the contour of your floor pans and have the correct thickness of insulation bonded to the backside. They come with the correct heel pad sewn into the drivers side and have the correct hem in the appropriate places.
*NOTE* 1969 - 70 Cougars did not originally come with a sewn in toe pad like the 1967 - 68 Cougars. These carpets do in fact come with the toe pad so if you want to be 100% correct with your car you would remove the toe pad.
FYI: Dark Brown carpet is what was normally found on cars with Nugget Gold interior.