I use a threaded aluminum standoff that is attachd to either the chassis top plate or to the speedo heat sink with a long set screw like 1/2 inch long. I use red loctite for the set screw into the standoff and a button head screw and washer for attaching the driver to the other end of the standoff.
If the driver is not quite located where is needs to be, I will use a piece of .060 inck thick lexan sheet as a shelf to relocate the driver figure.
Bob Oaks