There are plenty of old aftermarket cabs out there. Some have heat, a few have air. If you want a quiet cab with heat and air, trade up to a 4230. It is a late model 4020 with some of the 4020's weaknesses fixed. The front axle is stronger for loader work, there is a high low hydraulic shift available in the quad range,wet clutch and the hydraulics do not have the supply pump shut off if the clutch is pushed in.