Would this be any good for you? It needs a new battery, but I’m sure it was working when I took it off a bike (about a million years ago). The three “tang” ring is, I think, for 36 spoke wheels and the four “tang” fit 32 spoke (I may have that the wrong way round). I have another two harnesses as well, but only one of each ring
Make a donation to cancer research uk and I’ll post it to you.