Dont be misled,
I recently used the Duplicolor paint and it definitely is not a match!
It is close but obviously not even a match. I can show you the difference if you like.
If you really are looking for a match, you will have to go to Airstream and buy there 22 dollar a can OEM paint.
If you use the search feature and search grey paint you will find the exact match listed on this forum. And even more information to the effect.