This is just an addition to the AM8 upgrade I did based on the pheneeny design. I wanted to ensure that my bed was tracking perfectly perpendicular to the x-axis so I designed these little brackets that set on your 2040 extrusion and hold the bottom of the y-axis guide rod. You need to print two of these files so you can place one at the front and one at the back to ensure that your guide rod is perfectly straight. This places the bed almost perfectly in the center of the frame. I have also included the SolidWorks file so that you can customize the length if you need to locate your bed at a different dimension off of the outside frame rail.