OK, the facts. Em Deford started the E.L. DeFord brand around 1968 after a long career at Armstrong. In the early 70s he sold the brand to King and stayed on building flutes. After his non-compete arrangement was done he started the Emerson brand about 1978. The Emersons were new (Bennett) scale and had better headjoints but were very similar to the ELDefords. He got the earlier name back from King around 1981. The Emerson line really took off in the 1980s (I worked for him from 1981-84). Emerson was sold to Selmer in 1997 and later built at the Armstrong factory along with Artley. Selmer dropped all the special models such as the G treble, Bb and gold flutes (fantastic!). Since 1997 he made flutes and parts with names like Alpha, Amadeus (before they were made in China) and flutes of my brand along with Emerson-like models branded DeFord. Although he is in his 80s, he can make or restore anything and his greatest gift is tool making. He draws tone holes that are shaped like undercutting, one piece body ribs, custom heads, etc.
He is a great asset to instrument making and has enabled me to produce good playing flutes with custom keywork for a decent price. Helped me with the sax players key system and a flute with a low Bb.
I would say any of the ones marked E.L.DeFord would be from the 1970s and have a nice dark sound. At the time they were probably the best US student flute.