this bit ?
The actual 39 model was made from 1922 to 1938.
Be aware that the early versions of this ARE NOT safe to use with modern .22LR ammo.
If the serial number has an "HS" (High Speed) prefix it was made for modern ammo and you can shoot it.
Guns with no serial prefix at all or an "S" prefix were noted for their high quality and are worth more, but shouldn't be fired.
You can get an online current manual on the Marlin web site: