It fits the description I read in the tech thread, but it's on a '98 merc sable ...

 

Yes. It's the 130 amp version, as opposed to the 95 amp version of the 3G.

 

Went to the "go pull it" with the intention of bringing home a mark viii fan. Only one in the whole dang lot and the only thing missing off the entire car was the fan and shroud. On my way out walked the rest of the Ford car section and found this. Brought home ALL the power wire and about four feet of the other two wires. Thank you for your help in identifying the 3-g.

 

Got my 3G off a mustang last week. There were a lot of cars with missing 3Gs, but I only needed one.

It's funny because I only first read about the Mark VIII/Thunderbird fan here a few days ago. I can't ever recall seeing a Mark VIII, but Thunderbirds were very popular here in the SE. I guess it was a NASCAR thing. My family actually owned an '84, '92, and '96 SC. My Dad was a big Bill Elliott fan...

Seems like every junk yard around here has at least a couple 90s T-birds.

 

which thread does this reference?

 

This one.
ps://www.ford-trucks.com/forums/942250-just-did-a-3g-upgrade.html

 

Just want to check with y'all to see if this is wired correctly. I read the thread about the 3g upgrade, but the wire colors it mentions are different than what I have.


the last pic is the original connectors. Are these the ones everybody else is cutting off and covering the wire ends with electrical tape?

 

Probably. But I'm new around here so won't comment on all of the ones to cut off and not use until I've done it. But some are universally accepted.
Like the large Black w/yellow wire no longer being used. It's your old main charging wire and is being replaced by that Yellow w/white cable (6gauge-ish?) so is redundant.
Other end should go directly to the starter relay or positive side of the battery of course.

The White w/black (usually a stator wire) connects back to the alternator on that single connector next to the 3-wire connector.
I've seen some 3G's work only when that was disconnected, and some work only when it was connected. Probably some fault in the unit though, so leave it where it is per the harness for now.

Looks like you kept your Green w/red for the new alt and that's good. Should have 12v with the key in RUN and START, but not in ACC. Easy to verify with a meter or light.

That Orange w/LT blue is an odd duck from what I've experienced. Might be a Mercury only thing? Plain Orange used to be used for the external regulator's Field connection. Never seen one on a 3G though.
But the position is consistent with the Ford 3G's Yellow sensing wire location. So keep it connected to the large BAT output post under the big Yellow cable. Looks like that's where yours is already in the pic? Needs to see battery voltage all the time.
Looks like your original Yellow w/black wire could be your sensing wire, but I'd have to look at a diagram for your truck to be sure. If it is, you could connect it to the new Orange w/ltblu wire and make it more like Ford had it. But verify that first.
What year and model is your truck by the way?

So as far as the alternator, you should be good to go.

If I may say too, I would absolutely replace your main battery-to-engine ground cable at this time. It falls into the "cheap insurance" category for sure.
Yours has taken a licking and I'm surprised it's still ticking. Really has taken a beating over the years it looks like.
While it might still be working, it's deteriorating and will just keep losing efficiency until someday it'll fail completely.
It might have been too small for the load placed on it at one point and the outer casing melted off. Or maybe it was bare to begin with? Dunno, but it should be large and well protected.

Sorry if you know all this stuff already. I'm new (obviously) but your main battery ground cable is one of the more important circuits to have work, so figured I'd bring it up while you're upgrading things.
In fact, in the case of battery cables, I consider overkill to be just enough.

For our use, 4ga is a minimum. Yes you and Ford can get away with less, but for maybe a buck or three more, why not go big? I usually use 2ga on other people's rigs, and I had 1/0 welding cable on mine until recently. Running smaller 1ga cables now just because they can make tight turns easier.

For the sake of the most efficiency, the closer you can bolt it to the starter motor the better. Rather than up there under an alternator bolt. Here again, it "works ok" there, but not the best it can be.
I use one of the starter bolts on the 351M/400 setups, and a threaded hole just in front of the starter on many Windsors.

Hope that helps. Just came over looking for an under-hood lamp for my '79, but saw your alternator question and figured I'd chime in with my 3.5 cents.
Hopefully others will pop back in to correct any of that if I misspoke on anything.

Good luck.

Paul