The caboose, that seemingly noncontroversial conclusion to railroad trains, has touched off an unusually bitter public dispute between two Virginia legislators.

A state senator from Lynchburg has accused a senator from Portsmouth of having financial interests connected to cabooses. And the Portsmouth senator has retorted that his colleague from Lynchburg is a shill for railroad companies that claim cabooses cost too much.

State Sen. Elliott S. Schewel charged fellow Democrat Willard J. Moody with "an outrageous conflict of interest."

Schewel said Moody chairs a subcommittee considering legislation that would allow freight trains -- without cabooses and, at the same time, belongs to a law firm that last year collected $540,000 representing railroad workers whose union favors cabooses.

Moody, who chairs the Senate Democratic Caucus, angrily answered his colleague's charges, accusing Schewel of conspiring with the Norfolk & Western Railway to smear him in order to cover up dangerous working conditions at the company.

"The exaggeration and distortions of the facts by the Norfolk & Western Railway Co. and their willing tool, Sen. Schewel . . . are designed to cover up and sweep under the rug the [company's] deplorable safety and accident records," said Moody in an eight-page statement.

In Virginia, where legislative courtesy and gentlemanly conduct are a way of life, the acrimonious rhetoric of the caboose dispute has surprised many state politicians.

"I can't recall ever before seeing two members of the [General] Assembly publicly assaulting each other on their ethics," said one longtime political observer in Richmond.

The dispute concerns a bill at the last General Assembly session that would have repealed a 1914 state law requiring cabooses on all freight trains. Virginia is the only state where such a law remains on the books.

The state's railway companies, who argued that cabooses are properly a matter for labor-management negotiation rather than legislation, favored the repeal, as did Gov. John N. Dalton. But the union opposed it, arguing cabooses are an important work safety feature.

The bill died in the Senate but was held over for study by a subcommittee to which Moody was named chairman. His appointment caused concern at Norfolk & Western, which went to Schewel, who then also belonged to the subcommittee, with information about Moody's union connections.

As a result, Schewel and two other subcommittee members wrote a letter in July asking Moody to remove himself from the panel. Moody refused and last month cast the deciding vote in a 3 to 2 subcommittee decision to delay the bill for at least a year for further study. At which point Schewel resigned from the subcommittee.

"I think it's wrong, it's gross and it's blatant, and I felt compelled to say so," said Schewel, a first-term senator, in a telephone interview yesterday.

Schewel denied Moody's charge that he was being used by railroad interests, noting that he has no stock or other economic ties to the companies and has voted several times against bills they favored.

Moody, for his part, denied having any financial stake in the outcome of the caboose bill. He said "I'm not sure I'll vote" if the issue comes up again.

"But if I do vote, I'll support cabooses," added the 23-year legislative veteran.

"The whole incident points up the need for an independent ethics commission to determine what is and isn't a conflict," said Judy Goldberg, director of Common Cause of Virginia, a citizens' group that has repeatedly lobbied for stronger laws regulating conflict of interest.

Goldberg noted that under present state law and custom, the final determination of whether a legislator has a conflict always has been left to the lawmaker himself. Situations like Moody's, she said, "are by no means isolated ones."