After I posted the above, I went out to shop and checked the sight. I was wrong, Mad dog was right, it's an S1. I should not have questioned Mad Dog's knowledge of tang sights.I hang my head in shame.
READ THE BIBLE-IT WILL SCARE THE HELL OUT OF YOU! NO 99"s ARE JUNK, FDP NRA Endowment Life Member US Air Force Retired,Phantom Phixer