JimI wouldn't be the least bit surprised if there is even a third round size, and possibly several sizes of trapezoid.
The first 5 people to post pics on this thread of their clutch gear, being measured with calipers, will get a set to test.
I have friction material for a gear with .475" diameter holes for the pads ready to ship. If your gear has .535" diameter holes, or the trapezoids, there is no need to post a pic. I only have the one size available.