The 9N production began at the Rouge Plant, continuing with the 2N until after the war ( WWII ) in 1945 when tractor production moved to the Highland Park Plant. All 8N production, all FORD tractor production for that matter was produced at the Highland Park Plant up until 1967 when FORD closed the Highland Park Plant doors for good and moved all tractor production out to the north suburb of Detroit in Romeo, Michigan. The plant was called the FORD TRACTOR PLANT - ROMEO. Tractor production remained there up through the early eighties when FORD ceased to produce tractors there and by the 1990's the FORD name was completely gone from the new tractor market having been bought and sold numerous times...New Holland, FIAT, etc. The ROMEO plant is still in operation as the FORD ENGINE PLANT. Your wifes' friend may be thinking of the Dearborn Motors Corporation which was headquartered in Birmingham, Michigan, neighboring up to the city of Troy at the corner of Maple ( 15 Mile Rd. ) and Coolidge Highway on the southwest side. They had a big buildiing/showroom in front off of Maple and if you drove down Coolidge you could see the vast testing grounds behind the cyclone fence. As you came south to 14 Mile Rd. at Coolidge, there was a FORD tractor warehouse on the north west corner and turning to the west, just after you passed under the Grand Trunk Western railroad trestle, there was the old Sherman Bros. Manufacturing Company, which sold backhoes, blades, and bucket accessories. There was never a FORD tractor manufacturing plant in TROY. In the mid-late sixties, Dearborn Motors was dissolved, the new headquarters moved to Troy, not far from the DMC headquarters, and the new name was FORD TRACTOR DIVISION. I grew up two miles from DMC,in Clawson, Michigan, and dad would drive us by the showroom every Saturday afternoon. I miss my dad and those good ol' days. Charles Sorenson, Henry Fords' chief of production/right-hand-man, owned a farm in Clawson,I was told by Mr. Harold Brock. The DMC building is long gone, the property now divided up between condos and a shopping mall.

Tim Daley(MI)

I believe the Romeo tractor plant started tractor production in 1974 and ended in 1988.

From th eford web site:

The 2.2-million square-foot plant has more than 1,600 employees that produce an average of 2,900 engines per day and nearly 800,000 engines per year. Originally the Ford-Romeo Equipment Plant, the plant was built in 1966, and at that time the plant assembled tractor components. By 1983, the plant produced 300 tractors per day.

In 1987, the plant was converted to building Ford’s new modern family of modular overhead cam engines. In 1990, the first 4.6-liter modular engine was produced for the new 1990 Lincoln Town Car, which was named Motor Trend “Car of the Year.”