**sigh**
Murphy's diaphragms work on the single-chamber pods of a certain size only, for example the center vent pod on the 123 and 124 chassis. His kit will NOT work on the smaller size pods like the 124 diverter, or any of the 124 footwell flap pods (early or late).
For the dual-chamber pods, only the front half (small lift) diaphragm is replaceable. The rear (large lift) diaphragm is not replaceable, and GM's mickey-mouse "kit" reduces pod travel significantly. Of course he won't tell you that.
Photos are here:
http://www.meimann.com/images/mercedes/W124_dash/
Translation: Buy entire new pods.