Alternator solutions? Perhaps..

[Rattlenbang]

As I mentioned in another post, the O-ring between my alternator and vacuum pump was left out by a previous owner, and it turns out formagasket is no substitute. I have a call in to rocky mountain and waiting to see if the part can be had. I did a little digging, and for those who want a cheaper alternator substitute than the OEM one, the 2005 Ford Excursion diesel uses an electric vacuum pump for the brakes, and I found one online new for 60 bucks. You should be able to replace the stock Mitsubishi alternator with a local one, and use this ford vacuum pump for the brakes, likely for a lot less money. I would hate to do this for lack of an o ring (my alternator is new), but I don't have the specs for the missing o-ring to seek out a substitute.

[Rattlenbang]

After a lot more digging, I've discovered that the o-ring is a 16 X 2.5 mm. The internet is wonderful. For those who develop a leak here, you can get this part locally.