I can only speak for my '68 111 coupe, but I believe it is the same. The subframe bushing cover is #110 683 00 10 and the clips are # 001 988 44 78. I had one original that was cracked and it indeed had three metal clips. They are both available from MB as of 6 months ago. I chose to use only two of the clips because they are a very snug fit.
Interestingly on the 111's, they only use one cover on the right side. This is because the battery tray is mounted a 1/16" above the left sub frame bushing cavity and there is no way to get a cover on.