I think up to 2016 Airstream used the pewter gray and in 2017 went with black.
My 2008 is pewter gray. I purchased a can of pewter gray paint from Out-of-Doors Mart.
Kept the can inside over the winter and finally used it last month to touch up my tongue. Perfect match of color. I used a little wire wheel to remove some rust and then shot over the bare metal spots. I was kinda rushed to complete the job before a big trip but the paint has held well enough.
2008 Classic 25fb "Silver Mistress"
2015 Ram 2500 6.7L Cummins. Crew Cab, 4x4, Silver
2010 Tundra 5.7L, Double Cab, 2wd, White