This is the Turbine housing for the T25 and T28 series GT Ball bearing series. This turbine housing comes in either .64A/R or .86A/R sizes, made for internal wastegated ball-bearing systems.
GT(X)28R Ball-bearing series use 53.90mm Turbine wheel
GT(X)25R Ball-bearing series uses 53.00mm Turbine wheel
This turbine housing will not fit Garrett P/N 431876-5126 (Journal Bearing GT28R that uses the Ford-Style 5 bolt turbine housing and wheel.)
Turbine housing comes with actuator elbow to control internal gate door, but does not come with wastegate or wastegate clip system.
Please note the the following turbos can ONLY use a .64A/R:
GT2554R - (aka GT25R)
GT2560R - (aka GT28R)