Bendix Corp. appeared to be in the weakest position yesterday after another furious round of legal and financial maneuvering in its three-way takeover battle with Martin Marietta Corp. and United Technologies Corp.

Although Bendix struck first, its tactical situation now appears to leave it in danger of not just losing its bold bid to take over Martin Marietta but of being taken over itself, either by Martin or by Martin's ally, United.

A United spokesman said yesterday that his company believes "Bendix will withdraw its offer for Martin before the termination date, and Martin will then withdraw its offer for Bendix, leaving United Technolgies with the only offer outstanding." He declined to say why United thinks Bendix will back off.

Yesterday's events included Martin Marietta's announcement that it had been offered 63 percent of Bendix's shares in response to its counteroffer, the rejection by the Bendix board of a takeover offer from United Technologies, and inconclusive legal action in Detroit.

This was the situation with the three companies:

* Bendix could begin buying Martin Marietta shares tendered in response to its offer as early as next Friday. Bendix, which touched off the corporate showdown with its original tender offer for Martin Marietta, says its $48-a-share offer has been accepted by owners of of 58 percent of Martin Marietta shares.

Before purchasing the tendered shares, however, Bendix must survive a legal challenge next Wednesday in U.S. District Court in Baltimore, where Martin Marietta has filed a lawsuit alleging that Bendix's tender offer violated federal securities laws. The case is set to come before Judge Joseph Young on Wednesday.

Thursday will be the last day on which shareholders who have offered Martin Marietta shares to Bendix can change their minds and withdraw them.

If neither the lawsuit nor withdrawal of shares stops Bendix, another possible blockade could be raised. If another offer is made for any or all of Martin Marietta's stock, federal securities rules automatically would forestall the Bendix purchase for 10 days.

Under its mutual defense pact with United Technologies, Martin Marietta has agreed not to try to find anyone else to make such an offer, but United itself could make the rival tender offer that would block Bendix.

Even if Bendix succeeds in acquiring a majority of Martin Marietta shares, it still would be vulnerable to Martin Marietta's counterattack. Under the laws of Maryland, where Martin is incorporated, Bendix would have to wait at least 10 days before installing a new board of directors at Martin. During that period, Martin could buy the Bendix shares tendered under its counteroffer. But the laws of Delaware, where Bendix is incorporated, permit a new board to be installed immediately. That board then presumably would vote to cancel the Bendix attempt to take over Martin Marietta.

* Martin Marietta thus appeared to have several defenses: attracting a new tender offer, succeeding with its own bid to take over Bendix, or somehow ensuring its survival because of its pact with United Technologies.

Martin Marietta is offering $75 a share for 11.9 million shares of Bendix, a little more than half the Bendix stock. About 63 percent of Bendix's shares have been tendered in response to that offer, Martin Marietta said yesterday, but they can be withdrawn until Sept. 21, so Martin Marietta cannot begin buying them until after that date.

* United Technologies apparently has little to lose except the opportunity to add to its diversified industrial empire on favorable terms.

United came to the aid of Martin Marietta this week by making its own bid to buy Bendix. United offered the same price as Martin Marietta, $75, for the same number of Bendix shares. United and Martin agreed that, if the United bid succeeds, United then will sell Bendix's fuel-controls and jet engine starter divisions to Martin, as well as 1.6 million shares of Martin stock held by Bendix, for $600 million.