Dissidents within the United Auto Workers union said yesterday that they will oppose efforts by their leaders and General Motors Corp. to erase traditional labor-management barriers at GM's proposed Saturn Corp. manufacturing complex.

Reducing job classifications, putting hourly workers on annual salary and taking other steps to diminish some of the differences in status between workers and management could eliminate the union's role within the nation's biggest car company in the long run, dissidents said.

Elements of those proposals were contained in a draft of a labor agreement between GM and the union's 25-member executive board, which is negotiating a contract with Saturn Corp. The company and union began rewriting the draft June 28, largely because of the UAW board's objection to pension provisions.

Whether the dissidents have the clout to block an agreement and, thus, wreck the Saturn project is unclear. What is certain is that the dispute does not stem from economics. It is a debate over whether the UAW should jettison its longstanding adversarial approach to labor-management relations in favor of a more cooperative program.

UAW President Owen Bieber and Vice President Don Ephlin, who is in charge of the union's GM Department, contend that a more cooperative strategy is needed to help reduce production costs that have placed U.S. auto makers at a disadvantage in the intense, small-car competition with Japanese rivals.

Saturn is envisioned as GM's attempt to revolutionize small-car production in America, both in terms of automation and labor-management practices. Success or failure of Saturn, scheduled to begin turning out up to 500,000 small cars annually by 1990, could determine the fate of small-car production in America, some auto industry analysts say.

But UAW dissidents like Peter Kelly, president of Local 160 in Warren, Mich., say that their leaders are going too far in their quest to help GM improve its competitive posture. "Inherent" in the Saturn labor proposals "is the demise of the trade union movement as we know it," Kelly said at a press conference in Warren yesterday.

Kelly said the UAW board criticized the draft agreement for the wrong reasons. "I'm saying that with this draft contract , the union will be absorbed into the corporation," said Kelly, who is also on the union's national bargaining team.

Local 160 Vice President Leonard Wozny put it this way: "We're attacking the basic philosophy of this agreement, which could cause us problems further down the road."

UAW leaders Bieber and Ephlin, in an apparent attempt to cool tempers, said in a joint statement yesterday that no Saturn labor agreement had been reached. Any Saturn contract that is signed "must provide a high degree of income and job security for our members," the UAW leaders said.