Kapitan wrote on Oct 30^th, 2011 at 8:00pm:

Never noticed? but thats one of the main features of the 707 What yu mean "pylon" are actually turbocompressors fitted on three of the engines, to provide extra air for cabin pressure, air conditioner and bleed air to engines. The engine nr 1 didnt have a turbocompressor. Neither any of the 4 engines of the DC8...for example. The turbocompresor is a main exclusive 707 feature.

For the DC8 that's wrong! It has turbo-compressors(4) located in the front of the fuselage(Did you notice the air intakes in the nose?). The re-engined DC8 have no turbos, they are replaced by two packs! I flew the DC8-55 and 72CF in real life(I'm a former flight engineer)before to fly the DC10.
Cheers