Gear Install on 9" Question

Ok, I have installed gears before, but this is my first 9". As I pulled it apart, I noticed that it is a very simple rearend and wouldn't be hard to set up at all. Well, I went from a 3.45 gear (large pinion/not very thick ring gear) to a 4.40 gear (small pinion/thick ring gear). I'm to the point where I'm trying to set it up for the correct backlash. The problem is, I can't get the ring gear close enough because it wants to hit the metal ring that holds the tip of the pinion. Here's a pic of the ring I'm talking about. See where the tip of the pinion goes through?

http://www.ford-trucks.com/articles/9inch/9in16.jpg

If I set it up to where it doesn't hit this metal piece, then it's way too loose. What have I done wrong here? I'm thinking that I may have over-tightened the pinion nut. It doesn't 'feel' too tight though. I'm going to loosen it when I get home and see if it drops the pinion farther down into the housing (meshing with the ring gear sooner). Could this possibly be it?

Here's a small pic showing the assembly together. Notice if the ring gear was slid closer to the pinion (like it needs to be for a smaller pinion) then it would come close to or hit that metal ring.

http://www.ford-trucks.com/articles/9inch/9in6.jpg

If you don't understand, I'll try to explain better. I could really use the help; I was trying to have the car back together before Thanksgiving.

Ok, I figured it out. The casting process must have left some excess material around that ring. Just a little bit of work with the grinder and all is well.