externally, the 401 and 425 are the same engine with the same stroke.
so, if you're not going to pull a head off and measure the bores, the only way to differentiate is with the engine code stamping.
The way to crush the bourgeoisie is to grind them between the millstones of taxation and inflation.
Government schooling is about "the perfect organization of the hive."
H.H. Goddard, Human Efficiency (1920)