Look, you are dealing with a bad alternator. Part of the problem is whether you go with the 60, 75, or 80 amp unit, the alternator will not produce adequate power at idle to meet anything beyond basic electrical needs. This means the alternator is constantly being stressed out. The alternator overheats, which increases the strain on the voltage regulator, the bearings, the windings, and its inadequate output causes strain on the battery too.

There is a sticky, linked a long time about a real upgrade, one that is a lot less likely to leave you jump starting the van on a cold December morning because your battery went dead because the factory alternator did not fully charge it and it froze. But since we are on the subject, here you go.

Fuel Injection Technical Library » 3G Install Tech

RJM Injection Tech — Alternators

The real differences between most of these alternators is which mount type they use. Once you identify your mount type, the rest is quite simple. You will also need to swap your original pulley onto the new alternator. My 4.0L Aerostars use the side mount type. To be honest, I would take one of the 160 amp models, because it means your alternator is actually producing more than your stock alternators peak output at just idle. In addition, as the article above linked points out, it also reduces the fire hazard the older 2g alternators had.

To really do a 3g alternator right, you need to also run a replacement charging wire from the hot terminal on the alternator to the battery + terminal. The stock one is not very heavy duty, and you could potentially burn out its fusible link under a heavy load situation, such as a low battery. This same company does sell an upgrade kit, or you can build your own using some battery cable. If you build your own, make sure you get a good large inline fuse to match it. The kind used in high end stereo amplifiers will work fine so long as the amperage rating is high enough. I can't recall the fuse rating, but the kit that RJM sells comes with the fuse holder and two fuses.

RJM Injection Tech — Alternator Charge Cable Kit

You can use the stock harness, but just keep in mind that because the output is so much higher than original, there is always the possibility that it could burn that fusible link, and you wouldn't realize anything was wrong until the battery light comes on.

https://www.ford-trucks.com/forums/7...lder-aero.html

If you don't upgrade to a 3g alternator, at least run the highest output 2g you can.