Well I compared the color charts to a picture of a freshly painted Cummins and it does appear that XF67 Buff is the closest. Of course, there's always the excuse of colors being slightly different on the computer, but since both pics are on the computer, it should be fine!
Edit: Just noticed that the XF colors are flat, and I want a glossy look, so the best for that is X31 Titanium Gold.