I put together a little information on the cruise control servos used in E34's and other BMW's. Included are some pictures and diagrams. Here is where you can download the pdf
Cruise control actuator - Technical information
This is still in draft. I've include a few pictures showing how to remove the actuator from a 540i without tearing apart the headlight and grill. Please let me know what you think, (i.e. what's missing? mistakes? what should I do to make it better? etc.) On the other hand, maybe not so many care about the internals of these devices (they just happened to catch my fancy...)
Hope you find it useful!