With T4 sized turbochargers, there is no performance advantage to changing the exhaust manifold to match... So, why go to the expense? Our adapter flange makes for an inexpensive alternative to replacing the manifold and allows for quicker changes back and forth from T4 to T3 turbos. The large foot print of T6 turbo can be bolted to a T4 manifold or a T4 Turbine Diverter Valve with our dual throat adapter flange. Machine cut flat to 0.480, our adapters seals in exhaust drive pressure. PartNumber : bdd1044106 Description : T4-T3 Adapter Flange Category : Turbine Flanges Engine : Duramax 6.6L 11-17 LML-LGH-L5P Make : Ford Title : Adapter - T4-T3 Manifold Flange Suggested Product : 1045995-T4 Fabrication::Flanges