Great Plains Gasification Associates, developers of one of the nation's largest synthetic fuels plants, has submitted a proposal to the Federal Energy Regulatory Commission that would settle a dispute over how gas customers would be charged for the plant's construction.

The proposal, submitted last week, would conform to a ruling by the U.S. Circuit Court of Appeals for the District of Columbia earlier this month that prohibited the energy commission from allowing the North Dakota project to go forward. The 3-to-0 ruling said that gas customers couldn't be charged for plant construction before they received the gas, as the Great Plains firm had suggested, and the energy commission had approved in November 1979.

The developer's pricing proposal was opposed by energy users including General Motors, the New York Public Service Commission and the Ohio Consumers Council. The project's opponents said customers shouldn't be charged for the plant before they actually receive the gas and that the project should try to secure loan guarantees.

At a meeting yesterday, the plant's developers explained the proposals to its opponents in hopes of reaching a settlement of the issue with them and with the energy commission so that the project wouldn't be tied up in court again, a source said.

All sides agreed to meet on the proposal at a later date, the source said.

The developers have received approval from the Department of Energy for $1.5 billion in loan guarantees for the plant conditioned upon approval of the project by the energy commission and other factors, the source said.

The plant would convert a low grade of coal into gas.