Rob, did that kit repair/workaround the brackets welded on the muffler? If so can you share where you found it?
Sorry for the delay - I just now saw your question.
I found the repair kit on ebay - there are a couple more available at item 201296235900
You will need to grind off the existing square 'cages' that held the original nuts. I used a flap disc on a 4" grinder and they were gone in no time. I also had to grind off some big fugly mounds of brass brazing that the PO had tried to use to hold on some nuts.
For future reference if the kits are NLA - the kit basically contains a set of M6 socket head machine screws, wave washers, M6 rivet nuts, and round spacers to raise the heat shield off the muffler. As Robert said, you could probably assemble your own kit with an online visit to your favorite industrial parts store. You also will need a metric hand rivet nut tool to compress the rivet nuts. I used an Astro Pneumatic Tool 1427 - also available on ebay.
The rivet nuts need a 3/8" hole drilled at each location. As the original thread mentioned, you may need to drill into internal pipes at one or two locations. The front stud mount on my muffler was in good shape so I left that in place and used it as the baseline reference. I mounted the rivet nuts one at a time and checked the alignment of the heat shield using the spacers under the heat shield after each fitment. (Keeping in mind that the holes will be oriented differently than if you just held the heat shield flat on the muffler and marked holes without the spacers in place.)
For final installation, I used copper anti-seize on the inside of each rivet nut.