General Motors will invest about $US300 million to upgrade a factory in Tonawanda, New York, so it can build two new six-cylinder engines starting in 2005, Bloomberg News reported. GM spokeswoman Kathy Bommarito told Bloomberg that the 3.5-litre and 3.9-litre V-6 engines will be used for undisclosed vehicles beginning with the 2006 model year and about 720 of the plant's workers will be retained to assemble the engines.