I've obtained what I thought was a 1979 460 that was externally balanced. Turns out it's a pre 79 internal balance motor. Switched out the hatchet spacer and flexplate. What I have a concern with is that the new harmonic balancer is not sitting very flush with the end of the crank. I'll measure how far off it is later if needed. Were the hachet crank spacers longer the the pre 79 smooth spacers? The smooth crank spacer that is on the engine currently is 2.775" OD length. Is this correct? Any input would be appreciated!