[KGBnut]

Not to contradict Charlie, but depending on your climate, the exhaust manifold heaters as shown in his pictures may be plenty good enough...and are likely more readily available. Where I live in Connecticut, I drive my '30 Coupe year round with a heater very much like the Auto-lite in this pictures.

Look at your firewall, just behind the exhaust manifold. Don't be surprised if your car already has a hole there from somebody installing a heater long ago.

Ken