This is evidence of interpreting “J” as a “1” as opposed to interpreting “J” as “Jesus” meaning “since the time of Jesus”. In other writings, you can see “I” for “Iēsous” which is Greek for Jesus but has the same meaning.

Image is from a collection recently released by the British Library. Source

Monument To Gustavus Adolphus Kempenfelt Esq.

On the twenty-ninth day of August J782, his Majesty’s Ship the ROYAL GEORGE, being on the heel of Spithead overset and sunk; by which fatal accident about nine hundred persons were instantly launched into eternity: among whom was the brave and experienced officer Rear Admiral KEMPENFELT….

https://en.wikipedia.org/wiki/Richard_Kempenfelt States:

Richard Kempenfelt (1718 – 29 August 1782) was a British rear admiral who gained a reputation as a naval innovator. He is best known for his victory against the French at the Second Battle of Ushant and for his death when HMS Royal George accidentally sank at Portsmouth the following year.

Edit: For those who believe the “J” above is just an old numeral for 1, please see another example from this medieval coin.

( https://www.reddit.com/r/CulturalLayer/comments/jo07ev/evidence_of_1000_years_added_to_the_official/ )