Thanks, wibgradio99 and Ken. On commutes through there in the late 80's I wondered who had those three sticks just off I-95. I'd always thought they were 1540's.
From old logbooks and coverage maps, all of which had WFLN as 'D-3', I'm gathering that the due south null is in deference to omni WJWL in the south of Delaware. They signed on in the early 50's ; WFLN a few years later.
Near JFK Airport in Queens even before sunset, WJWL could come in louder than WFLN was -- daily, I submit, if and when we'd ever tune in.
Again -- much appreciate that tower tip!
(Peculiar & maybe O/T note: The WJWL owners put on super-Top 40 WAMS several years after WJWL. WAMS was nearly impossible to hear up in Queens because their signal all went south. I heard 'em exactly once in all those years, with a few seconds of a gurgly 5:00 sign-on, when a fiendish cackle and flip of a switch from local WBNX NYC's sign-on neuralized them.)