I have seen this deal 4-5 times in the last 5-6 months. They seem to rotate the 20% straight discount and the 35% gift card, and a few other combo's, in a regular rotation.
Phil, if you up your head PN quantity to 2 , then you ought to see the $560 gift card.
With all of these AZ discounts, the shipping is free. If you live in a state with any Autozone presence (store or warehouse), then you'll also pay your state sales tax on this. Still, a very good deal. Use the card for a new intake, new gaskets, and so on.