I have a 747 book around here somewhere that mentioned 742s and 743s built after a certain date had the more advanced engine nacelles from the 767s. I can't seem to locate the book to get specifics though.
Also maybe they were retrofitted. Iberia uses the 743 to MMMX. I am sure the 743 needs a lot of extra power to get out of Mexico City during the summer. Unless the 743 below is planning to depart next fall it will need all she's got to get out of this hot and high airport.
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