This might seem like a strange question, but I've always wondered: Why are the engine pylons different on the #2 and #3 engines on 707's? The pylon comes all the way to the front of the engine nacelle, as in this picture.
Photo © Kjell nilsson
I haven't seen any pylons like this on other jetliners, nor have I seen jetliners where the outboard engines have standard pylons, and the inboard ones are different. Is this simply more favorably aerodynamically, or does the longer pylon house some sort of equipment. Any insights would be appreciated, since when I know the answer to this question, I'll no longer have to lie awake at night thinking about it!