[blucar]

The only heater that Ford used in '37 was the hot air type which operated with a heat exchanger system that was attached to the right exhaust manifold.
This system has a lot of draw backs, plus the parts are hard to find and expensive. In 1938 Ford came out with a hot water heater which works very well in the earlier cars. The '38 style of heater was used through '39, in '40-41 Ford came out with a larger hot water heater that was mounted in the center of the firewall.
The firewall mounted battery box makes it difficult to use most after market hot water heaters, however, the small '37 heater will mount to the center of the firewall with no difficulty.
I have a '38-39 style of heater in my '36 coupe... It looks great and works good.