Wow! Nice find. You'll have to give us another typecast when you get it all cleaned up.
It's been said that Coronas made in 1941 were repainted in that brown crinkle finish by the factory. Look at this link, halfway down the page: http://sevenels.net/typewriters/s-coronas.htm
On my monitor it looks more gray than tan, but I do remember seeing a few tan ones in the past. Congratulations! Great typewriter.
Great find. Timeless design, looks as modern today as it did back then.