My 1950 Price Information guide (updated to 1/19/51) shows two factory heaters as described by the others. It is worth noting why you may see alternatives because in 1950 dollars these were a pricey accessory.
Heater Dash-Type Deluxe w/defroster $39.80 Installed
Heater Airflow and Defroster $64.10 Installed
To give you an idea of how steep that is a deluxe cab was only $51.90
