Not sure what Ive got: 727 or 904

Very, very easy. Get down and look at the passenger side of the pan. The 904 side pan rail is straight along the side, but the 727 has a large bulge in towards the front of the side rail

Here:
727 on the left of the photo




Many filters come with both gaskets. The 727 is on the far right, the gasket actually "upside down" but you see the bulge