You will need to use the
96 Brochure for 97 coach, coach's made during those years did not change between coach years.
If you look at the tanks themselves you may see a stamping on sidewall of tank as to tank capacity, most HW tanks were 6 gal unless it had a 10 gal option.
Using
this link will lead you to a Newmar search option where you can ask a question with a 1997 question where you may get a answer from a 1997 owner as to the capacity's from 1997 coach.