87 300sdl turbo cruise control actuator & amplifier location
 

Can you tell me where to locate the cruise control amplifier and actuator on an 87 300 sdl turbo? The cruise control was intermittent on this vehicle and would frequently work when the steering wheel was telescoped, I changed out the switch to no avail. I anticipate that either the actuator or amplifier have failed but I am not sure where they are located on this vehicle or what they look like.
Thank you.