I just received my gorgeous new Bosch alternator from Mercedes shop. It is identical to mine, came with a new Bosch internal voltage regulator, but did not come with the little black box with the wire going to the "+" terminal and bolted to the rear of the alternator.

I took mine off to look at it and I assume to swap it over to the new alternator. It's rectangular and says nothing at all on it. The wiring terminal does say, "amp" and "180984".

First of all, what is this thing? Secondly, mine is cracked on the outer shell, is this a problem? Thirdly, why do you suppose the new alternator doesn't come with this? I think I'd like to get a new one before I install this.

Thanks!