Moving front spring eyes rearward

I have been told that on my very stock 69 car. Never considered it as there are "No" mods at all in axle and drive train location. No vibes while driving.

The front yoke of the drive shaft would seem to be to far out as pictured but pure stock! The longer rear balloon tranny seal is not used. What is the real engagement length required? Any one know what that dimension is?

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1'' FROM BEING BOTTOMED OUT IN THE TRANS.