The United Transportation Union, which represents more than 8,000 Conrail employes, yesterday floated a new, not very clearly defined, plan for the purchase of the federally owned railroad.

The plan, outlined in a 1 1/2-page press release circulated at a House Energy and Commerce subcommittee hearing, calls for a public sale of Conrail, allowing Norfolk Southern Corp., CSX Corp. and Union Pacific Corp. to buy, in equal shares, a major portion of Conrail's common stock, but specifying that none of the railroads would have a voice in the operation of Conrail.

The UTU release quoted union President Fred A. Hardin as saying, "We have been assured by a majority of the proposed participants that the plan will work and can be accomplished very quickly."

But spokesmen for Norfolk Southern, CSX and Union Pacific said that did not include them.

The release also said Transportation Secretary Elizabeth Hanford Dole and appropriate congressional committee chairmen are aware of the plan. DOT Deputy Secretary Jim Burney said that the agency was aware of the plan but added that "really, in terms of the details of it, we are still completely in the dark."

The DOT has worked hard on behalf of a plan to sell Conrail -- officially Consolidated Rail Corp. -- to Norfolk Southern for $1.2 billion. The deal, which would create the nation's largest railroad, was approved by the Senate last month.

Both the DOT and Norfolk Southern said yesterday that they prefer that approach to the UTU proposal. "We're still quite convinced that Norfolk Southern is the best buyer," said Burney. Bob Fort, assistant vice president for public relations at Norfolk Southern, said, "We wouldn't buy it unless we had complete control and a voice in running it."

CSX has opposed Norfolk Southern's proposal to buy Conrail, which was created in 1976 after the collapse of the Penn Central and six other northeastern railroads. CSX is among 43 investors in a counter-proposal organized by Morgan Stanley & Co., which has bid $1.4 billion to buy the railroad and ultimately sell it to the public over a period of years.

"We have not been involved in the development of the proposal," said Tom Hoppin, assistant vice president for corporate communication for CSX, who said that the company's officials only learned of the proposal from telephone calls yesterday.

"We certainly endorse its premise, which is an independent Conrail," Hoppin said.

Thomas A. Saunders III, a Morgan Stanley managing partner, said that Conrail has the best operating record of any major railroad in the country and should not be split up, which he said he believed was implicit in the UTU proposal. "That would be an absolute tragedy."

The UTU release said that the Norfolk Southern deal "will never get necessary approval in the House" and also predicted failure for the Morgan Stanley proposal.

Of its own proposal, the release said, "UTU sincerely believes that this would be a sale of Conrail that would satisfy the administration, the members of Congress, the shippers and the employes."