Thought I'd start a thread for these as they seem hard to find. I did find that there is a much wider selection of 1 3/4" clamps instead of 1 5/8". A friend gave me a set of 1 3/4" clamps and with small square of 1/8" rubber on either side they fit quite well. I made some speaker mounts out of them (attached pics). I'm still searching the web for better deals on these, I'll be sure to pass along my findings. Maybe else has info on where to find clamps and what other stuff works.