81->78 xs400 engine swap - alternator wires

[armyofda12mnkeys]

So the only work I was really looking at when I was swapping an 81 engine to a 78 XS400 was replacing the points based system by putting in the electronic ignition to hook up to new engine...

So as I was hooking up the rest of the regular wiring before I even attempt that, I realized the alternator on the 78 engine had a different alternator wiring setup...

On the old 78 one it had one 4-input female and 4-output male wires coming out of alternator (which is recieved by a 4-output and 4-input wire on harness)...

But the 81 alternator wires coming out the engine, one of the wires has only 3 on the female end (so i guess it had 3 on the male end on its original harness) but my 78 wiring has 4 ...

Can I just hook this up and expect it to be powered correctly lol?

The other person who did a 81 electronic ignition swap only added the coil governer to his 78 engine, so the alternator wires were stock 78 ones. So running into territory that hasn't been gone through so I thought I'd ask the forum.

Here is a pic showing that 3-input female end from the new engine and the 4-output male end on my battery:

I did see the 'alternator cover' #1 here http://www.boats.net/parts/search/Yamaha/Motorcycle/1978/XS400E/CRANKCASE%20COVER/parts.html

is the same till 1982... hmmm guess the electronic parts are different then. I wonder if I should put in the alternator from the 78 onto the 81 model, then it'll have a 4-input female input on that one plug as needed.

EDIT:

So that 1 wires has 3 wires going into the end connector when on the 78 it has 4... the extra wire on the 1978 seems to power the headlight? relay assembly ... So I just swapped out my 78 cover and put it on this engine since Im using the 1978 harness (with just 81 electronic stuff spliced into the harness to go along with the engine).