6.4 Jeep SRT8 Exhaust Manifolds

The earlier 5.7 manifolds will have the smaller square ports and are a different kettle of fish. My understanding is the 6.1, 6.4 and 2009 on 5.7 all share the same D-shaped exhaust port configuration with possibly some minor variances in EGR and such things. You can used the d-port manifolds on the earlier square port heads if you address EGR issues as the d-ports are bigger, but going the other way is not going to be the best for flow as you will be introducing a big restriction at the transition from head to manifold.