777 Engine
CR2 is right on target as he is is most of the time. Can't get a 777 engine through the side door on another 777. It will fit in the side door of the 74 with about 2 inches to spare on the top, I have watched them go in and out on more than three occasions. Also the nose door allows things like oil drilling equipment, radio towers, wind generators etc. I would not count out the 74 for many years to come, but that is just my opinion.