Dallas at Philadelphia is listed as even. San Diego has opened as 4-point favorite at home against Oakland. Neither line is expected to move before Sunday's conference championship contests that will determine the Super Bowl participants.

"If there's any change, it would be Dallas," said Bob Martin, the "head linesman" operating out of Las Vegas. "If that game were to become 1 point, Dallas would be favored. As for Oakland and San Diego, you currently can find 4 1/2 in a few places. San Diego has become a popular team, like Dallas."

There is no secret as to the popularity of the Cowboys and the Chargers. They have pizzazz. One was "America's Team," however briefly. The other features a lightning bolt on its helmet. Both play with a great flair on offense, are not afraid to gamble, love to throw the ball, and have slashing-type runners. They project the wide-open style so dear to the heart of most armchair quarterbacks.

Philadelphia and Oakland, by comparison, are dull. They are almost a throwback to what made teams great before the rules changes at the start of the 1978 season. They rely on the defense to keep the team in the game until the offense can generate something in the way of points.

The responsibility of the Raider and Eagle defenses Sunday will be to keep their much more explosive rivals from breaking the game open early. Conference championship games often are played conservatively through the first 15 or 20 minutes. I doubt that Don Coryell or Tom Landry will go that route. They will come out firing.

If the Cowboys and the Chargers are to fulfill their popular destiny, it is important that Tony Dorsett and Chuck Muncie have productive outings. Dorsett is particularly dangerous on synthetic surfaces such as Philadelphia's. Both runners have been known to commit the costly fumble. Muncie is a threat to lose control every time he handles the ball. And Dorsett has been lucky, in his last two games, to have fumbled without Dallas losing possession.

The Eagles must keep the Cowboy running game in check and apply some pressure against Danny White's passes. White's throwing can be very good, or very bad. The Raiders must keep the Chargers from scoring with the long strike. San Diego has difficulty getting into the end zone from the opponent's 10 or 15.Its offensive line, while exceptional at providing pass protection for Dan Fouts, does not block that well for the run. Oakland must make the Chargers settle for three or four field goals.

The most important factor, however, in handicapping these championship contests has to do with weaknesses, not strengths. For all their glamor, the Cowboys are terribly vulnerable on the corners and the Chargers are more than suspect at left-side linebacker and at the left corner.

Dallas and San Diego are as good defensively as their front fours make the rest of those units appear to be. Both fronts are effective at shutting down the run and applying pressure to the passer. But any team capable of neutralizing those defensive fronts is going to expose the linebacking and secondary play of the Cowboys and Chargers as being, indeed, secondary.

Philadelphia and Oakland have offensive lines that are good enough to do just this. Neither Ron Jaworski nor Jim Plunkett will ever become my favorite quarterback, but they have enough tools at their command Sunday to take advantage of the Dallas and San Diego weaknesses. The Eagles and the Raiders have running games that merit respect, and their receivers are more than adequate to exploit the Charger and Cowboy secondaries.

And, should these games come down to a final test of "character" in the closing moments, I will be content to side with the Eagle and the Raider defenses. They have been the best in the NFL all season. They perform with great intensity and pride. If they are beaten, it will be only because in the 19th week of the campaign, they were confronted with the NFL's most high-powered offenses. They will not beat themselves.

Make it $1,500 on the Eagles, even, and $1,500 (imaginary, of course) on the Raiders, getting 4.