Does this 2005 Altima 3.5L have two cats or three? The ACCD can't seem to make up its mind. The one I saw had three, and a D-193-96  on the firewall-side manifold. The radiator-side manifold had an aftermarket cat too, but it was impossible for me to get an angle on reading its EO#. Both of the aftermarket cats looked to be Mickey-Moused together, with the end of the cat shell cut off and the remainder welded rather sloppily to the bottom of the exhaust manifold flange. I rejected it, but I can't seem to erase it from my thoughts.
I really don't remember Altima 3.5 having EGR, Maxima yes. The ARB page for that year shows 2 or 3 cats, they can't make up their mind. And ARB still shows 2003 350Z as having 1 converter. ARB is very sloppy sometimes.