An exemplary exhaust test tog apparatus includes a housing defining an exhaust flow path extending from an inlet to an outlet. At least a portion of the housing is selectably rotatable relative to an exhaust aftertreatment system. An arm extends from the housing into the exhaust flow path. An exhaust probe configured to measure an exhaust constituent is coupled with the arm and positioned at a location in the exhaust flow path. An actuator is configured to extend and retract the arm to vary the location of the exhaust probe in the exhaust flow path. The exhaust probe is moveable to a plurality of locations within the exhaust flow path through a combination of rotation of the housing and extension and retraction of the arm.