The pilot bushing hole is in the center of the flange that I am measuring. The pilot bushing hole measures the same on the 440 as does the 383. I forget exactly what that was but I do know they matched.I have tried another BB and even a small block flex plate and it is too small on the 440 flange also. They all fit the 383 flange as the guy at Brewers said they would, small or BB should fit. The only part I have that fits that 440 is the flex plate that came off it. The only way my present flywheeel or any other flex plate will fit is to open them up from about 2.16 (the measuremnet of both the center holes on the BB and SB plates) to 2.19 to fit this flange. The flange doesn't appear to have had anything done to it out of the ordinary. Its fairly round, with a slight taper toward the flat of the flange, as the 383.