I don’t know if you’re still looking, but I was recently given a Waterloo chest and top box. My son and I cleaned it up, put a little paint on it, new wheels, oiled it up and I found the two missing slide retaining clips on eBay. I can’t figure out how to copy the url with my phone, but plug the listing below into Google and it’ll take you to the page.
(2) -WATERLOO, MATCO, MAC, PROTO TOOL BOX DRAWER RETAINING- KEEPER SPRING CLIPS