wiring to voltage regulator

[Mike Soultanian <msoultan@xxxxxxxxx>]

Ok, I'm mildly confused.  I just swapped engines from my 76 to my 78 and 
there is a difference in the wiring that goes to the voltage regulator, 
namely the wires that come off of the plug.
I'm going to do this from memory, so hopefully I don't forget anything...

this is on the 76 engine: What I noticed is that there are 4 wires 
coming from the alternator.. red, green, brown, and black.  The first 
three go directly to the plug.  Then, I think spliced to the red wire 
(or green wire) from the plug (that goes into the regulator) there is a 
blue wire with a spade connector.  The black one is also a spade 
connector.  These blue and black wires were both connected to something 
in my 76 bus wiring harness.
However, when I put the 76 engine in my 78 bus, there's only one wire 
available on the wiring harness, a blue wire.  I believe that this wire 
comes from the dash and supplies the alternator warning signal (not 
totally sure).  I couldn't find it on the bentley wiring diagram, 
though.  Nor could I find the black wire that comes from the alternator 
in the bentley.
So, now I'm left with a 76 engine in a 78 bus, a blue wire coming off of 
the regulator plug, a black wire that is with the other 3 alternator 
wires (presumably coming from the alternator), and a blue wire that 
comes out of the car's wiring harness.
does anyone know what these wires are or why the 76 wiring harness has 
two connectors and the 78 has one?  I will eventually head over to the 
bus with a tester and figure it all out, but I thought I'd get a 
head's-up first.
Thanks,
MIke