New twist on phantom extension courses that helped bring the Pac-10 down on several member universities: Ben Apuna, former Arizona State linebacker, files a $2 million suit in Phoenix accusing former ASU officials of negligence for having him sign up for such a course.

One of eight Sun Devil players given academic credit for an extension class in 1979 they did not attend, Apuna claims involvement cost him a shot in three postseason bowls and adverse publicity hurt his negotiating posture with the NFL.

Now, Arizona State is on two years' NCAA probation and Apuna is one of Canada's 2-14 Toronto Argonauts . . .

Probation? NCAA tapped Texas Christian yesterday for one year, but no hard sanctions (citing TCU's clean record for 45 years). "One unhappy player who failed to make his grades and left campus almost three years ago" piped up "two years later" with raps against Horned Frog recruiting, says Chancellor William Tucker. Accused Charles Fenske, basketball assistant, denies wrongdoing but is denied recruiting privileges off campus during probation . . .

Georgia and Georgia Tech follow the academies' lead, shift Nov. 28 game to Dec. 5 to open an NCAA-on-ABC football doubleheader with Army-Navy. National exposure for Herschel Walker after the Heisman voting . . .

Alabama fullback Ken Simon: the law student accusing him of unloading shotgun fire over a traffic incident is asking an arrest warrant. . . . Former 'Bammy Boy Richard Todd, Jet quarterback, is named in an assault complaint filed in Nassau County, N.Y., by the New York Post. NFL, too, is looking into Todd's shoving reporter Steve Serby against a locker Wednesday . . . In Dallas, a judge has ordered Thomas Henderson, injured-reserve Miami Dolphin, to pay $1,226 to a barber who said the ex-Cowboy smacked his head Dec. 6, 1978, when requested to stop telling a dirty joke in the presence of women customers . . .

Yankees finally sign Jerry Mumphrey, celebrity benchee in mid-World Series, to that long contract -- and, who needs it with Ken Griffey in hand, a Steinbrenner spokesman says Big George's "present intention is to not participate in the Nov. 13 free-agent draft." The better to pursue their own reenterers, the spokesman added, probably meaning Reggie Jackson and Ron Guidry . . .

It's HBO live, ABC delayed for S.R. Leonard-Bruce Finch in Reno Feb. 15 . . . CBS-in-RFK yakkers Sunday: Jim Kelly-John Dockery . . .

Coach Gerry Gimelstob previews George Washington's 1981-82 basketball team in public scrimmage Saturday, 1 p.m., Smith Center . . .

A. NCAA says no Division I punter ever averaged 50 yards for a season; Iowa's Reggie Roby, at 50.2 this midseason, has slipped to 49.5 . . . Q. Last world title fight in Reno?