Second post, but I have loved the site since I bought my 06 F350. Today, I confused the heck out of the guy from Omally's. My alternator died. For the last year, if I didn't drive it for a few days I would have to jump it. I dropped in two new Optima's and had them check to see if it was charging, but it was still doing it. I figured it was the goofy ghetto alarm that was on it when I bought it. Today the battery light flashed and the radio lights flashed and kaput. I pulled the alternator off and took it to Checker/Omally's or whatever they are called this year, and the guy showed me a different one than the one I pulled. I entered the VIN number on the Ford parts site and got a list of what Ford says it had, and that is the one he showed me. The one that is supposed to be on it is a Motorcraft GL-648, and the one that I have is a Motorcraft GL-966. The post is on the back instead of the top left. Maybe the previous owner replaced it?

Does it matter which one I get? Are the plugs the same for the wire harness? And I can't even find a GL-966 online that isn't remanufactured. I like to buy online, but a warranty online is a pain. If there was a national chain I could order from and take it back if it breaks, it would be great.

Also, why not go with the 140AMP unit? I don't have a big stereo or offroad lights, but it's way cheaper. Amazon has them for just over $100. Even though, I'm not going to get a remanufactured unit. It's one thing when you have a Chevy small block in a truck that takes 15 min to change, but this thing (for me) is a nightmare. Big arms, little brain syndrome. Honestly, the guy who designed it couldn't make the shroud pop off so you can even see what your doing? My nine year old is about the right size to work on it.

Thanks for any help you guys could give me. I have to drive from Yuma AZ up to Utah in a few weeks and thank goodness it crapped out now!

 

Something I found says the GL-966 is a 2005 only. Is yours a very early 2006?

But then, so is the GL-648. So this one website says, anyway.

GL966RM: Alternator. 6.0l 363 cid 8 cylinders, 110 amp, from 9/15/04, w/ radial adaptor - Electric/Electrical Alternator and Voltage Regulator - Ford Motorcraft Alternator/generator. GL-966-RM, GL966RM, 6C3Z-10346-DARM, 6C3Z10346DARM.
GL648: Alternator/Generator : Alternator & Voltage Regulator. Electrical. - Electric/Electrical Alternator and Voltage Regulator - Ford Motorcraft Alternator/generator. GL648.

I'm not so sure about the diesels, if it was a gasser I'd say if the wires reach, and the connectors match, go for it.

Could it be something weird like one is the optional second alternator and the other is the primary?

 

It was made in 5/05. Weird. I'm going to the Ford dealership to ask them this morning and sort this out. I'm driving a hybrid while I'm fixing my truck and they are as fun to drive as that chair my grandma uses to go up the stairs. Same speed, too. Gotta get this thing done! Thanks for the reply!