I was looking into this a few weeks ago also. When I browsed the web places said the oem one is 110-120. But I talked to singer alts and He checked his sources and he says our stock alt on the 2010 focus is a 150amp alt! I was going to order a HO also but he didn't have a case that would fit our model.
May I never boast except in the cross of our Lord Jesus Christ,
through which the world has been crucified to me, and I to the world.