WARNING: This page is about a different car, the 2008 Dodge Magnum, 2008 Dodge Charger, and 2008 Chrysler 300. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Firing Order/Cable Routing - 5.7L
Courtesy of CHRYSLER LLC
The firing order is 1-8-4-3-6-5-7-2.
These numbers (2) and (3) can also be found on the top of the intake manifold (1) to the right of the throttle body.