In the days when it was regularly contested in Montreal's Forum or Toronto's Maple Leaf Gardens, the Stanley Cup final exuded a special class that set it apart from other sports events.

Even Boston Garden or Detroit's Olympia provided a fitting locale for hockey's ultimate confrontation. To the people in the building and to those hundreds of thousands who celebrated afterward with a victory parade, this was the most important event in sports.

Now that the Stanley Cup has found a home in Nassau Coliseum, something is missing. The electricity no longer crackles through the air; instead, obscenities are more likely to fly.

Islander fans, perhaps as a result of an inferiority complex prompted by Ranger mania, take pride in their mindless behavior, from the initial drowning out of the national anthem to the final derogatory chant directed at officials or opposition.

Club officials conduct the Stanley Cup playoffs in a manner more likely to be encountered at a St. Patrick's Day party. Hangers-on routinely pour past dressing-room guards, leaving the media helpless to fulfill its function. For the past two seasons, the NHL has publicly proclaimed its embarrassment, while professing inability to cope with the disaster.

The players have been less than careful about Stanley Cup tradition. Clark Gillies took the cup home and permitted his German shepherd, Hombre, to use it for a water bowl. Bryan Trottier took it to bed along with his wife, who reacted to the cold shoulder by tossing it into the backyard, where neighbors came over to pose for pictures.

Neighbors who cared, anyway--a year ago, the fourth game of the Stanley Cup final against Minnesota attracted 550,000 viewers on New York's Channel 9. A routine Yankee-Kansas City game playing opposite on Channel 11 drew 1.2 million. During late May on Long Island, most folks think of ice only when it is clinking in a glass.

But if NHL bigwigs routinely resort to antacids after the annual parade along Hempstead Turnpike and Merritt Parkway, they had better obtain another supply, because it would take an upset of Lake Placid proportions to pry the cup away from Trottier, Mike Bossy, Denis Potvin and friends this spring.

Not only do the Islanders have the NHL's best team, they also are beneficiaries of the coin tosses that determined home-ice advantage for semifinals and final. The Islanders are blessed with the odd home game in every series they play.

Step one toward a third straight Stanley Cup begins Wednesday, in the opener of a best-of-five competition against Pittsburgh that promises to be a mere formality.

A more testing series will start April 15, a best-of-seven matchup against either Philadelphia or the New York Rangers. A lot of folks around New York hope the Rangers can repeat the miracle of 1979, but the Islanders gave notice in Monday's 7-3 romp at Madison Square Garden that this is mostly wishful thinking.

Next on the agenda will be a best-of-seven semifinal against the Adams Division champion, with Montreal the probable opponent. This should be a good battle, but the Canadiens' chances would be greatly enhanced if they had the home ice.

Edmonton and Minnesota most likely will be contesting the other semifinal, with the North Stars receiving the extra home game. Then, sometime in May, as late as May 27 if it goes the limit, Long Islanders will take time off from cheering the Yankees and Mets to once more fill the Stanley Cup with champagne.

The folks on the island might even accept it with a touch of class this time. That would be the biggest upset of the playoffs.