I've learned a lot putting new engine mounts in Nellie. One, it's not a hard job. Two, selecting the proper engine mount is critical.
Nellie's factory-original Cushyfloat mounts had no model number.
The first new set of mounts, Cushyfloat 17-1609-65's, were dramatically noiser than Nellie's factory-original Cushyfloat mounts. I then removed the 65's and installed Cushyfloat 17-1608-45's. The graph below compares the wheelhouse noise level with each mount type.
On average the 45's are more than 50% quieter (-12bB) than the 65's.
Why? Because as the graph above shows, they're better at dampening the engine's vibration.
Bottom line, Nellie has never run quieter or smoother.