GM Service Manual Online
For 1990-2009 cars only

Object Number: 264979  Size: SH
    • A datum is an imaginary horizontal plane that runs 2 ways to the vehicle:
        Below
    • Parallel
         Calculate the height dimensions at right angles from the datum to a given control reference point on the underbody.

The company that develops height dimensions determines the location of the datum based on the equipment used. Different datum lines are established for the same vehicle. Add or subtract an equal amount from all height dimensions. Create a new datum line for your usage.