Burbank-based Shamrock extended its $42-a-share offer for...

Burbank-based Shamrock extended its $42-a-share offer for Polaroid Corp. to Jan. 9. The offer had been set to expire Dec. 29. Shamrock said it had received 6.9 million Polaroid shares as of Wednesday . . . USX Corp. said it completed the $600-million sale of its transportation subsidiaries to a new company controlled by Blackstone Partners, an investment group . . . Nissan Motor Corp. said it will raise prices on its 1989 cars and trucks 3%, or an average of $388, effective Jan. 4 . . . Atlanta-based Cox Newspapers rejected a new proposal from a group of out-of-state investors who want to buy the Miami News. The newspaper is scheduled to shut down after its last edition Saturday.