In each of the pictures above, the Original neck is on top and the All Access Neck on the bottom. The fretboard lengths are the same in both, but the necks vary in where they attach to the body. Notice that the original neck's base was shorter, with the fretboard extending out to fit the body. The original body had less routing, whereas the new All Access Neck requires deeper body routing up to the neck pickup. On the All Access Neck, the additional neck wood is needed to allow it to be bolted closer to the bridge. The Heel Joint on the Original necks are at the 16th fret and the neck thickens at the 12th fret. The Heel Joint on the All-Access-Neck is at the 17.5th fret and the neck thickens at the 16h fret. You cannot retrofit an original neck into an all access body. You could however, retrofit an all access neck into an original style body with heavy modifications of the body first.