I have an R&D damper plate, used 2 summers, in good shape. It was on a Westerbeke W46/ Hurth HBW150. 10 splines, 155mm OD.
I was pretty pleased with it as it eliminated the low RPM clatter.
I paid $245, I'd like to get $70.
I'm repowering so lots of W46 parts (except the crankshaft and 1 con rod)