Some 3G's on certain applications have a pulley close to the same size as the 2G's, but pretty much all of the reman'ed parts store alt's have the larger pulley.
You could try finding a very thin washer to put behind there, but that reduces the amount of thread you'll have available with which to crank the retaining nut down, so I wouldn't recommend going that route. Your best bet is really to just hunt the boneyards for any and every mid-90's and above Ford and see if you can find a pulley of equal size on a 3G alternator.
I was working at Autozone at the time I did mine, so I was able to just dig through the core bin at my workplace until I found a suitable donor pulley, and just swapped that for the big honkin' pulley that came with my reman'ed 3G. (I seriously doubt the reman company would give a crap, they appear to put new pullies on all of their alt's.) If you've got a buddy working for a parts store, you could maybe have them keep an eye out for one for ya', but again, your best bet's going to be with hunting the 'yards.
...or you could just special-order the pulley from a place online that has a specific-sized pulley, but 1. it's more expensive, and 2. I don't remember the name of the place right off hand.
