The difference between the different diagrams relates to the different lamp types and whether it is a two or four lamp system.

Since you are posting in the Restoration forum I'm assuming the lamps are standard sealed beams or halogen sealed beams. On these lamps you will see on the glass lens of each lamp three little projections for the aiming machine. The lens may be marked DOT or SAE depending on how old they are but not VOL or VOR. Therefore the target light patterns without a machine are the top ones shown in the diagram below (from Virginia regs).


Draw lines on a flat surface 25' from the lights per attached diagrams from the '68 Plymouth shop manual. Using the left drawing aim the lows beams. Then cover the lows and aim the highs alone.