I just dealt with this because I bought a wing kit from around that vintage. Yes the change happened in 2001 with the introduction of the RV-7. Parts commonality between the 7 and 8 was the reason for the design change.
There's no hard date for when they stopped shipping the old style wings though. It's understandable that they would want to finish off the stock of old style parts they had already made. As I did, check with Van's to see what wing a person has.
There's also a difference in aerobatic gross weight. 1550lbs vs 1600lbs.
Empennage Passed Pre-close Inspection
Wings mostly done
Dash 8 day job is financing the RV-8
Donation till September 2021