If you don’t have any luck go to the google box and type in screw in block heaters. A bunch come up. If you don’t find what you are looking for you can always modify you radiator and install one

1970 Duster
Edelbrock headed 408
5.984@112.52
422 Indy headed small block
5.982@112.56 mph
9.42@138.27

Livin and lovin life one day at a time