3.9-Liter Engines: The Ford 3.9-liter engine was either a 3.9-liter V8 engine designed in part by Jaguar or a 3.9-liter V6 engine designated under the Essex engine class and was introduced as a modified version of the original 3.8-liter Essex V6 engine with the same bore but slightly increased stroke.
3.9 Essex V6 - This 3.9 Essex was born in 2004 and ended its short production life in 2007. The 3.9 V6 engine was found in the 2004 Ford Mustang and 2004-2007 Ford Freestar.
AJ30 / AJ35 - This was the Ford 3.9 V8 engine for sale in the 2000-2006 Lincoln LS, 2002-2005 Ford Thunderbird, and the Ford Forty-Nine concept car. This engine received variable valve timing (VVT) and electronic throttle control in 2003 which gave it an added 30 hp over the older V8 engine. The Ford 3.9 V8 engine was rated at anywhere between 252 and 280 hp at the crank.