The German group catalog has the bottom pad listed as 113 914 0314 (left) and 113 914 0414 (right). The back pad as 113 914 0116 (no distinction for right or left)
SLS lists them for sale, but there is no indication of the source. (Euro 116).
I checked at Millers as well, they have pads listed, bottom right, bottom left, and back, each at US$ 110 (as of the last update of the catalog) You can call Kevin O'Brien and he should be able to give you the scoop on the origin and latest price.
Jonny B
1967 250SL Auto