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Hey Guys, i’m wondering if you guys can tell me how i’m supposed to know what amperage my alternator is, 40, 50,60, or 70 amp. Is this a case of more is better? And what’s the deal with an internal or external regulator? Does that even make a difference? It’s not quite time to replace it, but it’s starting to chirp and I figure one of the internal bearings are going bad, so I won’t be long. This is going in a 1986 F150 XLT lariat, 302, Auto with a AOD, it’s all stock too. I’ve had this question in my brain for a little while now, and hoping you guys can help me figure this one out. Thanks in advance.
Just go to a site like autozone or some other one, you can see they have pictures. The internal regulator alternator has different wiring connections. Most of the 1986 trucks I have seen do have the internal regulator type alternator. These alternators are expensive, and you might run into some wiring modifications anyway, these are the 2G alternators that were famous for catching on fire. Most of the internal regulator alternators are 65 amp, but they do have some that are 100 amp. You can check, but they are usually bigger in diameter and won't fit unless the truck was optioned for it.
what’s the deal with an internal or external regulator? Does that even make a difference?...
Well, it depends if you want your charging system to work. Otherwise, no, it doesn't make a difference.
Here's an example of an external regulator. This is mounted separately from the alternator, and is located on the inner fender just aft of the battery. It's right next to the starter relay.
Here's an example of an "internal" regulator. I used quotes because "internal" is a bit of a misnomer. The unit is mounted directly on the alternator, but actually on the outside. On other brands it is truly internal, inside the alternator case. But in all examples of an "internal" regulator, a more accurate description is that it is not "external", as in mounted separately from the alternator:
Edit: If your truck takes an external regulator, that will be sold separately from the alternator. If your truck has an internal regulator, that is almost always included with the new alternator.