JC Higgins over and under 20 GS barrrel number 103.370 with p437 also on it it is a a Winchester?

The 20 ga JC Higgins 103-370 was made by Marlin. It is the same gun as the Marlin Model 90. P437 is the serial number. P indicates the gun was made in 1957.

Prior to WWII sears sold the gun under the Ranger name.