I've looked through the Dealer's Bulletins that are available on the web site, and I didn't find anything indicating what color the shutters were. I do not have access to the salesman's data book, but it sounds interesting.
One interesting note was a mention of "painted fenders" (meaning painted a color other than black) were being introduced, as improvements in paint allowed for color matching in the field. Was 1930 the first year this was available on a regular production model? I know painted fenders were available earlier, but not common.
So far all I've learned is that all the shutters were painted black except for the ones that weren't.