Well, there is a lack of 64 gun ships generally and in the Royal Swedish Navy there were ten ships in the Wasa-class by Fredrik Henrik af Chapman. They varied a little in the number of guns from Wasa:s (Not the one of tipping over fame) 60 guns, to 62 and 64 for the others. Those had a little less draft, a higher lower gun deck to handle firing in high seas and a largely unprotected upper gun deck making it lower than usual for ships of the line. It could have heavy guns to be able to hold its place in the line, 36 lb and 24 lb guns, but some had 24 lb and 18 lb.

The ships:
Kronprins Gustaf Adolf (62), Fäderneslandet (62), Ömheten (62), Rättvisan (62)(Captured by Russians and later British), Dygden (64), Äran (64), Försiktigheten (62), Dristigheten (64) (Rebuilt to carry 74 guns, 1806), Manligheten (64), Tapperheten (64).