sorry i guess i was a little high on the amp output, not quite 200 but a good upgrade nontheless.
a post i saved courtesy of Bugzturbo
"The patient: `86 F-250 w/6.9L IDI engine.
My alternator was on its last leg, so I decided to upgrade to a 3G internally regulated unit since I run higher wattage lights, power inverter for charging cordless power tools, high power stereo, winch and run dual red top Optima batteries. I do this swap on most of my cars (Mustang, Thunderbird, etc) and other peoples, so I tend to keep a nice stock of them in my garage for spares, along with their pigtails. I could not believe how easy this was compared to all the splicing, running new wires, MAX fuse install, etc of the Mustangs and such.
Now keep in mind, this is aimed more for the "junkyard jewel" crowd since doing this with new parts would be expensive and defeat the purpose. I had the 100a large case alternator on my truck, but I think all the diesels do, so that shouldn't matter. The SMALL case 3G from a 3.8L Ford Taurus is a DIRECT bolt on. It's a small case with extended ears to fit a large case mount. These are found on early to mid 90's Ford Taurus with the 3.8L engine (maybe 3.0L too, can't remember off hand). Grab the alternator from that car, but then go find a `92-up Crown Victoria/Grand Marquis WITHOUT the police package (ie, 98% of what you're going to find in a junkyard anyway). They also use a 3g alternator, but with a completely different mounting system as these cars have a 4.6L engine that mounts the alternator in the valley of the engine. Now, unplug/unbolt the alternator harness from the alternator, then follow it back. You will find a junction block and a single round 2 wire plug. Unplug it and unbolt the hot lead from the junction block. You're done at the yard.
Unplug your harness and remove the factory alternator. Swap the pulleys on the old and new alt (you MAY need to grind just a tiny bit on the 3G's support ribs on the front for ample clearance of the V-belt pulley. Mine was REALLY close, so I just touched it up a bit to make sure it had plenty of room). Now, trace your harness back and unplug everything. There will be a round 4 wire plug, a square 2 wired plug and a fusible link attached to the starter solenoid. Also unplug the external voltage regulator (you can also remove the regulator at this time as it is no longer needed). The rpm signal lead will be in the harness to and will need to be unplugged if you have a tack in your truck. Now, unwrap your original harness. You will see where the hot lead that attached to the alternator goes down and meets up with a splice junction of other wires. Cut the lead to the alternator off of the splice, it is no longer needed. Leave all the other wires attached to that splice and tape it up. The other wire that connected to the alternator is orange and goes down to the voltage regulator. It is no longer needed. At the regulator plug, remove the yellow wire(s) and the green wire. You can clip them close to the plug. Toss the regulator plug and orange wire in the trash. Now, on the new harness you got from the Crown Vic, you will notice the round plug has a green and a yellow wire. Clip them both and toss the plug. Solder the yellow(s) of the old harness to the yellow of the new harness and the green to the green. Tape them up good. You're done already. Go reinstall the harness the same way it came out (you can retape the whole harness too for neatness if you'd like). Install the Taurus alternator and plug it in. Now, at the starter solenoid, you need to reconnect the terminal you removed AND the terminal on the hot lead on the new harness. And there you go. 130 amps of raw charging power.
What makes this so easy, and so different from other 3G swaps is that these trucks have a 3 wire regulator, not a 4 wire, so no need to bridge terminals like other applications. Also, the harness from the Crown Vic is the perfect length, PLUS, the wire is already gauged correctly for the amperage, AND it already has a built in fusible link rated for the higher amperage. No need for splicing in new wires and MAXI fuses like on other swaps. It's really VERY simple and should take no more than an hour to do. The 3G's are more reliable than the early alternators, and also put out more power at lower rpms and idle, which is important for our low revving diesels. Hope this helps some of you guys who were fearing a swap like this.
Bug "
