I'm making preperations to change the voltage regulator on my 1994 C220. I was trying to find the location of the voltage regulator...checked the back of the alternator and see nothing there!

What I see is a smooth plastic cover on the back of the alternator, would the the voltage regulator be located there under this cover? or is it possible that I have an internal voltage regular - meaning I have to replace the entire alternator :-(

Thanks,
Chandra