I'm looking for one of these Shure A45 Isolation Mounts.
Shure has one example of the A45 in our archive. The product was discontinued in 1986. Not many were sold, so finding one will be very difficult.
Try Ametron in Hollywood, CA. They have been a Shure dealer for years and are known for keeping old products on the shelf for decades.
Atlas-Soundelier makes a similar device, but it has no shock mounting.