There are several versions of the 18 tube 1937
The chassis with the optional Push Button Tuning has Automatic Frequency Control (AFC)
and can be selected from the preceding page.
There are also two versions of the chassis both with and without AFC, the difference being the tube type in the 1st audio stage.
If your chassis has a 6C5 for 1st Audio, the service information is HERE
If your chassis has a 6L7 for 1st Audio, the service information is HERE
You may need to explore each schematic to come up with your configuration.