[cassini] Iapetus
I suppose you mean equatorial trench, cause Iapetus already has an "equatorial ridge and centrally peaked crater" as you put it. Now if we found one with an equatorial trench... Interesting. I think it is just a common feature for some moons to have huge craters that look like death star guns. If you think about it, the Death Star isn't really that complex of a shape lol. So I'd say we are bound to find more moons that have craters like that. But that ridge is really something different.