Hy Donsz, the flywheel must be for a 454, as far as I know there are only two Chevy V8 engines which are externally balanced, the 454, and the 400 small block [not to be confused with the 402 big block]. I'm not sure if the flywheels are even interchangeable between the 400, and 454, but I do know that the 454 cannot use a flywheel that is not an externally balanced one, hope that helps.
