There are three connections on the back of this "internally regulated three

wire" alternator:

1) A big bolt with a plastic spacer and a washer-nut.

 This is the main power output and needs to be connected to a new heavy gauge

cable (at least 100A and multi-strand flexible is good). The positioning of

the connector is such that it will short out on the cylinder head unless you

cut the end off the bolt to just leave the minimum necessary to hold the

ring-end of the heavy duty cable plus one nyloc nut. You will also need to

use an insulated boot on this connector, an old HT plug boot held in place

with a tie-wrap works well. Even so this connector will  be very close

(about 3-5mm) to the cylinder head so always make sure the battery is

disconnected when adjusting the position of the alternator.

 The bolt (to be cut) also comes with a plastic cup-shaped spacer which

insulates the nut/bolt from the body (earth) of the alternator. We found it

works well if you junior hacksaw a section out of the side of this washer to

get the main cable ring as close to the bottom of the bolt as possible -

this lets you cut off the maximum amount of the bolt to give maximum

clearance to the cylinder head.

 You can route this heavy duty cable either way around the engine bay,

whatever looks neat in your insulation is ok. You should also include a

strip/mega type fuse (100A) as this cable will carry the main alternator

output. With the alternator on one side of the engine bay and the battery on

the other (RHD) this cable will be quite long, probably about 2.5m or so.

This length of cable will produce a (very small) voltage drop over its

length due to its resistance. THIS IS A GOOD THING, because this resistance

acts as a "buffer" to the charge rate to the battery if you're ever in a

position where the alternator has to charge a very low battery (e.g. after

you've had a jump start). When the battery is full (or near full) then the

small resistance is negligible, but when the battery is flat it can make all

the difference as to how well your battery will recover as it slows the rate

of charge.

 The other end of this heavy duty cable needs to do two things: it needs to

supply current to the ancillaries (i.e. via the loom) and also it needs to

charge the battery. It is important that this cable is NOT taken direct to

the battery +ve terminal but instead goes to where it can connect into the

existing loom. On Int MkIII (and probably others but don't quote me) the

right place is the input side of the heavy duty connector at the starter

solenoid (underneath the battery tray). This is where the original Jensen

alternator output wire went to and where several loom wires are also

attached. The cable up to the +ve battery terminal also originates here.

It's important that the alternator output cable goes to this junction,

rather than direct to the battery.

 The old brown wires (3 off, one thick, two medium) that were connected to

the old large alternator output terminal need to be connected together (a

nut and bolt works ok) and then insulated and taped up out of the way. They

need to be connected together because they feed fuse box "A 5/6" and "A 7/8".

This only works because the other end of the thick brown wire is still

connected at the starter solenoid end (to the new alternator output

wire/battery).

 2) A 6.3mm male terminal labelled "S"

 There are two terminals, one labelled "L" and the other "S". The socket of

these two terminals is designed to accept a block plug to wire into a

Mitsubishi loom. But there's no room for this plug so bin it and use a pair

of normal insulated female blade terminals instead. Looking at the rear of

the alternator the "L" connector is on the left and the "S" connector is on

the right.

 The "S" terminal is the sense wire. This is the input to the alternator's

internal regulator. It senses (reads) the loom's voltage and controls the

alternator's output accordingly. It's important that this wire is not simply

a wire from the battery/alternator output. It needs to sense the voltage at

the looms "main junction"; this is so that the alternator's regulator is

reading an average voltage (with voltage drops throughout the main part of

the loom) and can correspondingly raise the alternator's output high enough

to get the voltage in the main part of the loom up to about 14.5 volts

(exact values vary slightly by alternator type etc.).

 So, there's no point connecting the sense wire near the battery/alternator

output as that will always give a false (good) voltage and the alternator

won't raise the loom's voltage high enough. I don't know where the

originating connection is physically as it's buried somewhere inside the

loom (you can see where it is logically from the Jensen wiring schematic)

but at the alternator end it is a white wire that was the input to the old

external regulator. The chances are that you'll have to strip this wire back

inside the loom a way so as to get to good non-corroded connection but it's

important that it is found and that the wire you add to it (to go to "S" on

the alternator) has a very good connection (solder best, scotch locks very

bad).

 If the loom that this wire is part of is in very bad condition (especially

the dash-to-engine bay plug/connectors) then there's a good possibility that

the sense wire will be higher resistance than it should be which will tend

to make the alternator's output correspondingly a bit higher than it should

be (making the above "buffer" long lead even more desirable). This is

something you'll have to connect up and try. If the voltage at the battery

is very high (15, 16, 17v etc.) then this could be the reason why. If this

is the case then you may have to revert to just putting the sense wire to

the main connection at the solenoid. This will mean that you're not getting

the full benefit of the high alternator output but at least you won't fry

your battery (or yourself if the loom melts due to its high resistance

bottlenecks).

 3) A 6.3mm male terminal labelled "L".

 This second terminal is for the dash warning light. Connecting the bulb,

even if you don't actually put it in the dash (there's no Jensen hole but

some people have sacrificed their fuel flap warning light) is still

important. The light is wired with switched ignition +12v on one side

(doesn't matter which) and the other side to the "L" connector on the

alternator. When the alternator is not charging (either 'cos you've not

started the engine yet, or due to a fault) then the lamp will have ignition

+12 (or whatever) on one side and 0v on the alternator "L" output - so the

bulb will light up. When the alternator is producing an output then the "L"

will also be live so the bulb will have the same voltage on both sides so

will not light up. If your alternator is ever struggling to produce enough

output volts (slipping belts, old loom, all accessories on etc.) then there

will be a slight difference between the voltage on the battery-side of the

bulb and the alternator's side - this will make the bulb glow a bit so it's

a good indication of something amiss.

 The warning bulb also has another important role. The alternator needs a

small amount of current flowing through its field windings in order to start

the internal regulator. The current flow through the warning light is enough

to achieve this which means the alternator will start producing output as

soon as it's spun up by the engine starting. Without the warning bulb there

will just about be enough residual magnetism in the iron core to also

generate an initial current but not really enough initially at tick-over;

you'll have to blip the throttle to raise the revs before the alternator

will kick in.

 Just a final point to re-emphasise: even if you've done all of the above, it

will still be the case that most ancillaries will be fed via the old

existing loom so even if you're "sensing" properly and delivering good volts

to the main junction then you can still have problems (dim lights etc.) due

to the old high resistance loom/connections. If you do make any wiring

changes (e.g. relays for your headlights) or add new items (e.g. big cooling

fans or electronic ignition) it's important to add all new wires and to

terminate them all at the main junction where the big alternator cable is

also connected.

And finally, finally, always carry a fire extinguisher and good insurance...

Alternator wiring schematic