I rebuilt the dash unit on the workbench, installing the glass and the instruments. As I installed the unit on the back of the dash, I kept checking the tightness of the installation by wiggling the speedometer. It kept wiggling as I continued to tightened the dash unit. Finally, I got my head out of the dash to take a break. I then heard what could only be the sound of glass cracking. Yep, I had forgotten to tighten the speedometer to the unit.