Both the 289 and the 289 High Performance engine have the same casting number. Here is a website that will give you tips on how to identify [url]http://www.hipomustang.com/images/hipoeng[/url]

[b]289[/b] * Bore and stoke 4.00 X 2.87 * Two barrel Ford carb * Hydraulic camshaft * In 1965 the 289 became was now at 225 horsepower, larger four barrel carb and a compression ratio of 10.0:1 This engine was available till the 1967 model year. [b]289 HiPo[/b] * Available from 1964 to 1967 * Higher nodularity content in block w/ larger two bolt main caps. * Counter weight balanced crankshaft. * 3/8 inch rod bolts * Screw in rocker studs w/mechanical lifter camshaft. * Dual point distributor. * Ford 480 cfm four-barrel carb atop a cast-iron intake manifold. * 271 horespower at 6,000 RPM w/312 ft-lb's of torque. Here is some more information regarding 289 engines [url]http://www.classicmustang.com/casting_numbers.htm[/url]