* Check your owner's manual: This is the most reliable source.
* Look at the fuel tank door: The sticker on the fuel tank door sometimes lists the capacity.
* Consult a reliable online resource: Websites specializing in automotive information (like Edmunds or Kelley Blue Book) might have specifications, but you'll still need to specify the exact trim level of your truck.
Without knowing the specific trim level of your 1997 Dodge Ram, I cannot give you a precise fuel tank size.