Please insert an image into your reply to show the measurement you want to make. What global direction is the stack compressed: x, y, or z?
Let's assume the compression is along the z axis. Plot the Directional Deformation along z-axis and scope it to one end plate body. That plot will show the minimum value in the Details.
Insert a User Defined Result and type the expression name, UZ, for directional deformation and subtract the minimum value. The variable names are listed when you highlight the Solution branch of the outline and click the Worksheet button.
Now you have a directional deformation that starts at zero at the blue end and has the largest deformation of the end plate at the red end.