High School Overtime Rule

[paulsonj72]

When did the overtime rule in High School football change(if using the 10 yard line procedure) to the ball becoming dead on a turnover. I ask because in reading an old newspaper story I saw in 1977 in Minnesota a team won by 12 points in overtime offer scoring on their first possession and then scoring a defensive touchdown.(And IIRC I saw a game end with a 14 point margin in 1985).