I am often wrong, but when I look at it I think:The one that goes between the header and the down pipe would be the exhaust manifold flange gasket, walker part number 31378, as shown in
http://info.rockauto.com/Walke...8.jpgThe exhaust pipe flange gasket goes between the catalytic converter and the mufflerOn the stock set up, there is half donut gasket on both ends of the catalytic coverter pipe, one at the header, one at the pipe to the muffler. The one at the header is bigger. Here's a pic of the two from when I replaced my cat.looking at the website again, I don't know which is which