Within the next 48 hours, the Yankees are expected to make new contract offers to two of their biggest free agents. The Yankees' exclusivity period with both Jorge Posada and Mariano Rivera ends after tomorrow, and yesterday Hank Steinbrenner reiterated that new proposals to Posada and Rivera will be submitted before the period expires. The players' current offers are comparable. Rivera will be offered a three-year pact for $39 million, while Posada's offer will be for approximately three years and $40 million. Earlier in the week, Steinbrenner told The Post the Yanks would be offering Posada and Rivera big deals.