Q: WHAT YEAR DID AHAZIAH'S REIGN END IN JUDAH?
A: IT DEPENDS WHAT CALENDAR YOU ARE USING!
On the Gregorian calendar (the one you might have on your wall) the year was 838 BC.
On the Hebrew calendar, sometimes called the biblical calendar, the year was 3209 AM.
I Kings 22:51 - Ahaziah the son of Ahab began to reign over Israel in Samaria the seventeenth year of Jehoshaphat king of Judah, and reigned two years over Israel.
2 Kings 3:1 New King James Version (NKJV)
3 Now Jehoram the son of Ahab became king over Israel at Samaria in the eighteenth year of Jehoshaphat king of Judah, and reigned twelve years.