[leadpenny]

I agree it could be a 727 (not 100), but the mounts suggests it is the center engine. The mounts on side engines in pic above are too close to the fuselage.

[ab01]

Maybe the center engine, but I doubt it. My recollection is that the center intake was blended into the tail, Now, if you want to discuss the 747-400, I still have my manuals. Distressing whenever anyone from the aviation community goes west.