I have SRT8 manifolds on my 2006 5.7. The ports are different shape but they work. I useds the 2009-2010 exhaust manifold gaskets, since they are D-shaped-- fit the SRT8 manifolds... BUT also have the EGR port. Make sure you make a notch in the passenger side manifold and your good to go.
And you also have to trim part of the transmission off, but its not that bad.... aluminum and cuts easy.
2006 Limited 5.7, SRT8 Manifolds, 3'' custom walker quietflow system, Crazy Jay Cam, Inertia Performance Heads, Airaid intake tube w/ KN drop in filter, srt8 pushrods, bilsteins, diablo