Yes indeed I was looking at the wrong part! Thanks Steve
I just pulled it out and the p/n is 201 540 38 45 neither of the p/n's you mentioned. Made by Siemens, in Austria with a single 10amp fuse on top.
Is replacement in order given the symptoms I descriped above? The fuse is intact, but when I shake the OVP, there's a rattle inside (something loose apparently).
'91 300E, 211k miles