Alternator woes

Hey guys, I'm having a charging system problem that I hope you guys can help
me out with.

Now, I know the charging system is simple enough in my 1986 GTI that I
shouldn't need a lot of help, but, well, whatever.

My car has ceased to charge itself. The battery and its related cabling,
fusible links, etc are all fine, as indicated by the fact that if the
battery is charged externally (by trickle charger or jumper cables) the car
runs just fine, until the battery runs down and the car dies. So I picked
up an alternator from Advance Auto, swapped it in, and I still have no
charging effect.

Now, I have a couple issues with the new alternator that bother me.

First, the old alternator has a small plastic box screwed to the back, with
a black wire connecting it to a spade terminal on the alternator marked +.
The plastic box is marked with a bunch of stuff, including a line reading
"2.2uF 100V", indicating it's a smoothing capacitor of some sort. The new
alternator does not have this piece. If it's just a smoothing cap, is this
critical? i.e. would lacking this part cause the new alternator not to
charge my battery? If it is critical, does this part have a name? I have
not seen it referenced anywhere, in the Bentley manual or on the web.
Should my new alternator have come with it?

Second, the old alternator had the blue wire for the idiot light connected
to a spade terminal labelled D. The new alternator has an empty hole marked
D with no spade terminal, and a different hole marked W that _does_ have a
spade terminal. What gives? Am I supposed to hook up the blue wire to the
W terminal now? I suspect not... Regardless, seeing as how it's just for
the idiot lights, I left it unconnected until I can verify how it needs to
be hooked up.

So basically, I now have the new alternator in the car with only the red
wire from the starter cable connected to it, and it grounds through the
engine. Ive done a little checking with a voltmeter, and I've got good
clean continuity from the Battery + to the alternator B+ (through the
starter), and good clean continuity from the Battery - to the alternator
housing. Still no charging effect, and I'm not sure where to look next.

Sorry for the long-winded question, thank you all in advance for any
assistance you might provide.

Mike