The Denver Broncos, those Mile High Kids with a rookie head coach, a recycled quarterback and a soda pop defense - as in Orange Crush - play host Saturday to a Pittsburgh Steeler team that doesn't scare anyone but its fans these days.

The oddsmakers say Red Miller's bucking Broncos are three point favorities in their first ever appearance in the playoffs after 18 frustrating seasons (WRC-TV-4 p.m. EST).

The quarterback, Craig Morton, knows a lot about frustration.

After failing to win complete respect at Dallas and with the New york Giants, Morton has encountered good fortune in his 13th season, his first at Denver. In 1977, Morton was the No. 2 passer in the AFC, throwing for 18 touchdowns with only nine interceptions.

The clear stastical evidence is that Denver has been winning largely on defense. The Broncos finished the season 12th in total offense in the conference, seventh in rushing, 14th in passing.

On defense, they were No. 1 against the rush, fourth in total resistance, but 12th against the pass. The Broncos finished third, with 150 points allowed, behind Atlanta's 129 and Los Angeles' 146, suggesting that Denver is tough backed up against its goal line.

At the moment, the Broncos' most pertinent victory was a 21-7 decision over the Steelers in the eighth game of the regular season.

Morton needed to throw only 12 passes and backup Craig Penrose two. Morton survived five sacks as he completed five throws, including a 20-year touchdown pass to wide receiver Haven Moses. Rick Upchurch, the team's big-play man, ran back five kickoffs for 167 yards, including a 87-yard touchdown.

Steeler quarterback Terry Bradshaw was sacked six times, the Steelers fumbled the ball away twice and were charged with 12 penalties in trying to cope. The Broncos survived 10 penalties, and Pittsburgh's only touchdown came with five minutes to play.

The tigers in the 3-4 Denver defense are ends Barney Chavous and Lyle Alzado, linebackers Tom Jackson and Randy Gradishar and cornerback Louis Wright.

On offense, the Broncos went down the stretch without injured Otis Armstrong, playing rookie Rob Lytle of Michigan alongside Lonnie Perrin of Washington, D.C. and McKinley high. Tight end Riley Odoms and wide receiver Jack Dolbin could surprise defenders who fail to respect their talents.

The Steelers will be making the postseason competition for the sixth straight year with a 9-5 record, worst of the four AFC participants.

Pittsburgh is 1-4-1 against the Broncos and their last loss in Denver was their third in three visits.

The oddsmakers make it close because they see two remnants in the Pittsburgh club which won Super Bowls in 1974 and 1975: a memory of having been this route before, and tortured pride.

The Steelers comforted themselves after last season's playoff loss to Oakland by dwelling on the obvious - that Franco Harris, Rocky Bleier and Roy Gerela were absent because of injuries.

This year, injuries also crippled this once-pound club. Bradshaw suffered a fractured left wrist and his remarkable 1976 stand-in, Mike Kruczek, was lost for the 1977 season with an injury Middle linebacker Jack Lambert missed several games with a bad and Bradshaw just had to preserve.

THe Steelers have messed up all season with fumbles (28), turnovers (47) and penalties (122), but when they get their act together they are tough. Ask the Dallas Cowboys, who took a thrashing from them.

On a day his control is good, Bradshaw calls up the memory of his two Super Bowl performances. Lynn Swann may be the best wide receiver and had his finest game in Pittsburgh's last Super Bowl, being voted the most valuable player.

Franco Harris some days can punch out a victory. He rushed for 1,162 yards in 1977. And if Rocky Bleier is not superstar talent, neither is he merely ordinary. He blocks more than his weight when he is not running.

Frank Lewis is ailing but there is good depth at wide receiver with John Stallworth. The Steelers' punting and placekicking are not inspiring, but the Broncos are advised not to arouse Mean Joe Greene, Lambert and their defensive mates unnecessarily.