The BladeForums.com 2024 Traditional Knife is ready to order! See this thread for details:
https://www.bladeforums.com/threads/bladeforums-2024-traditional-knife.2003187/
Price is $300 $250 ea (shipped within CONUS). If you live outside the US, I will contact you after your order for extra shipping charges.
Order here: https://www.bladeforums.com/help/2024-traditional/ - Order as many as you like, we have plenty.
If I took a guess I'd say 2007-2008. Alongside the Dura Tech 20CV ones.
In 2009 there were Aus8 ones.
According to a SOG BLOG from January 22, 2007:
"This is one of the first production knives to be manufactured from Duratech 20CV, a powder metallurgy stainless tool steel. It contains a large volume of extremely hard vanadium carbides, which increase wear-resistance. How tough? Try 35% greater than S30V, a super steel in its own right (e-mail us for a complete test report).
SOG Team Leader
Also available in 440 C stainless for a great combination of performance and price."
So either SOG was calling their Aus8 "440c" in 2007 or they were using 440c and changed to Aus8 later.
All references to the Team Leader from 2009 appear to state "Aus8".
http://www.sogknives.com/blog/sog-team-leader.html