I purchased some epoxy on my way home this evening. I roughed up the inside of the brackets and the spacer blocks. I match drilled #30 the spacers to the brackets. Next I final drilled the spacers with a #12 bit. I mixed some epoxy and spread a thin layer on the inside of the brackets and installed the spacers. I used a piece of 1/8" aluminum angle to hold the spacers in place and then riveted them.
