Originally Posted by
tdracer
If I recall correctly (and we're talking old, old memories here), all the early 727s had the oval center inlet (both -100 and -200). At some point Boeing introduced the 727 Advanced with several updates - one of which was the round center inlet.
I can only speak about TWA. Our -100s had a round center inlet, all our -200 and -200As had an oval center inlet.