Transit of Uranus from Neptune
The only one who seems legit is the first date, October 38172. It appears somewhere in Transits, by Jean Meeus (1989), and some say that also in the SOLET webpage, but I can't find it either. Taking into account that, if true, it comes from a book from 1989 and probably is not very accurate, I wouldn't take that date as an exact thing.
The other dates I can't find anything.