You are talking about the main color of the safety card's cover, however, on the upper right corner, there is a small colored area with the revision number of the card.
Yellow was the color code used for the 738 safety cards introduced last year, however, now that Delta has introduced a single common safety card for the 73G and 738, the color is now a medium blue.
I wonder, with the new 737 safety cards, what is the revision number? The previous revision number for the 738 safety cards was 3, however, I don't know if the new 737 safety cards have a revision number of 4 or does it start over with revision 1.
[Edited 2008-11-15 18:51:44]