NAVISTAR <NAV> UP ON HIGHER EARNINGS OPINION Navistar International Corp's stock rose after brokerage house Sanford C. Bernstein and Co raised its earnings estimate of the company based on expectations of better truck orders and truck tonnage, traders said. Navistar led the active list with a gain of 1/4 to 7-1/4 on volume of 4.2 mln shares. Traders familiar with the opinion said that David Eisenberg, director of Sanford C. Bernstein and Co's institutional strategy committee, raised his earnings estimates to 80 cts a share for the current fiscal year ending in October. He expects Navistar to earn 1.20 dlrs a share next year. In 1986, the company lost 14 cts a share. Eisenberg was unavailable for comment.