The black spacers come in new kits, if you have the 7A/B/C wooden parts, then you will not have the spacers. The difference in noise is noticeable, but how much, no idea, didn't measure it.
The motor mount holes also have moved slightly in new kits, so the motor no longer sits against the sides of the printer. Which also reduces the noise from those motors. The material feed mechanism has also changed a bit so that motor also no longer rests against the case, and the woodn parts from the feed have less contact points with the case. Which also helps in noise reduction.