Heaters were optional up through the 60s. I bought a 60 ford pickup in 1963 without a heater. I don't know how the original owner stood the cold. It took me a couple of weeks before I could afford to have the Ford place put a heater in it. Till then, when the temp dropped down I would take a coffee can and fill it half full of pea gravel and pour kerosene in it and light it up. It was 5:00 AM and dark the first time I did it. I drove about 65 miles to the next town. Getting there I thought it was still dark until I got out of the truck and discovered the sun was well up.
The kerosene had blackened the windows. I was 19 and a knucklehead as most 19 year olds are...
