I seem to remember DC10s had 5-across in the central section.
Oh yes, memories of flying with United to the States in the late eighties sitting in the middle of that centre set. At mealtimes, the (even then) ageing flight attendant would shuffle down the aisle, using the cart as a sort of Zimmer frame and yell, "Whaddya want, fish or meat?" before slinging the choice expertly across the row.