The M4A3E2 Sherman "Jumbo" were developed as a support for the infantry assault vehicle based on the latter type M4A3. 1.5 inches of Front and side armor was welded on to the hull, and the differential cover gear ratio was changed to support the retrofit weight increase. The T23 turret armor was increased, along with the gun shield, giving the Jumbo its distinctive turret shape. The extra steel armor was welded onto the cast turret and reached a maximum thickness of 177mm. To cope with increased weight, an end connecters called duckbills equipped the track, and supported by reducing ground pressure. 254 M4A3E2 tanks were produced from May to July 1944, and employed by the U.S. Army in northwest Europe, and by the Free French. Some 76mm main guns were used by local units to retrofit vehicles, as it proved useful in the role of infantry support.