The first of the major deadlines in the takeover battle between Martin Marietta Corp. and Bendix Corp. arrives tonight.

Martin Marietta shareholders who tender, or pledge, their shares to Bendix by midnight will have the best chance of getting Bendix's $43-a-share offer for 45 percent of Martin Marietta. The deadline is known as the proration deadline, meaning that, if more than 45 percent of the stock is tendered, Bendix will prorate each tendered block of stock, returning shares that put it over the limit and paying for the rest. However, Bendix has said it might modify the offer and accept more than 45 percent of the shares.

The returned shares will be eligible to be paid for in the second half of the offer, which will swap 0.82 percent of a share of Bendix stock for each remaining Martin Marietta share.

Bendix, which has been given a slight edge in the battle by most Wall Street analysts, said yesterday it will announce Monday how many shares had been tendered to it. Martin Marietta shareholders still will be able to withdraw any tendered shares before midnight Sept. 16, however, should another offer come along, for instance. The Bendix offer expires Sept. 23.

The proration deadline for Martin Marietta's $75-a-share offer for a bit more than half of Bendix is midnight next Thursday. Martin Marietta plans to pay for the remaining shares through an exchange of stock. The withdrawal date for Martin Marietta's offer is Sept. 21, and it expires Sept. 28.

Analysts have raised the possibility that each company will wind up with 50 percent of the other, creating a stalemate that probably would have to be broken in the courts. Experts say state takeover laws tend to favor Martin Marietta in that situation.

All of the deadlines and prices, however, are subject to change.