I thought that the small bolt hole on one end came into being with the hydraulic lifter slants. But I could be mistaken.
I also think that the hydraulic lifter slants have the shaft oil holes in a different location radially around the shaft.
it is also mentioned in that article that the small bolt hole on the rear was initiated on the late mechanical cam slant rocker shafts.
If the rocker shaft in the motor under discussion has the small rear hold down bolt, and the rocker shaft is a shaft for mechanical rockers the rocker shaft oiling holes must have been in the correct orientation.
