A gas turbine engine is provided that includes a compressor, a turbine, and engine shaft, a gearbox, and a tower shaft assembly. The engine shaft is engaged with the compressor and the turbine. The tower shaft assembly is in drive engagement between the engine shaft and the gearbox. The tower shaft assembly includes a tower shaft, a first bearing, and a first gear. The tower shaft extends axially along a rotational axis. The first bearing is engaged with the tower shaft. The first bearing has a plurality of roller elements and an inner ring engaged with the roller elements. The first gear (FG) is engaged with the tower shaft and extends axially between a FG first and second axial end surfaces. A first interference fit exists between the first gear and the inner ring of the first bearing. The first gear is configured for engagement with the gearbox.