Also, does anybody have any advise on 3G vs 6G? what is the difference? benefits of one over the other?
The only differences in the two Ford alternators, is that the 6G got more heavy duty bearings, larger fan and a better vented frame.
The 6G diode pack has the same amp output per diode as the 3G. The 6G rotor and stator have the same contact area, as a 3G.
Where the 3G vs 6G confusion comes in, is that with the release of the
6th generation alternator, Ford updated the amp rating (see below).
Sellers know this, and take advantage of the higher rating and
stretch it even further, by selling standard small case 6G models as 130amp, making the buyer think they're getting the same output as a large case 3G, but in a smaller package. < Very misleading!
Also, as for it being lighter and having less rotating weight < It's only lighter w/ less rotating mass if you compare the small case 6G to the large case 3G. There's also small case 3Gs and
large case 6Gs.
Here's the approx amp output of said alts.
Small case 3G = Factory rated @ 95 amps, Actual = 120a peak.
Small case 6G = Factory rated @ 110 amps, Actual = 120a peak (usually
misleadingly sold as 130a)
Large case 3G = Factory rated @ 130 amps, Actual = 160-170a peak.
Large case 6G = Factory rated @ 145 amps, Actual = 160-170a peak.
The above numbers are for genuine motorcraft standard output models.
The large case 3G and 6G both use a DE frame (front housing) size OD:
148mm/5.82"
The small case 3G and 6G both use a DE frame size OD: 135mm/5.31"
The advantages of the 6G over the 3G are almost null for fox apps. The better cooling doesn't do much, because the heat failures of 3G alts were only in extreme applications, where the current draw demands were putting near max loads on the alternator and doing it continuously. The larger bearings aren't much of a benefit either, because the brushes will wear out and the slip ring groove way before even the standard bearings will usually fail.
Next time you get tempted by the small case 6G claims, remember you're getting the same alternator as the 95a small case 3G, with only better bearings and cooling.
You decide....