4.56's used to be the lowest gears for a Chrysler/Dodge 9.25" but last year Yukon released 4.88's. It never was an issue of them fitting it was just that nobody made anything beyond 4.56. One word of advice though, is to use a cross pin modified for 4.56 and 4.88 gears. Precision Gear makes one and it is well worth the money not to have to grind on the ring gear or the factory crosspin. As for pictures, I need to get on that project as well. I've been meaning to get some posted but I've never been much of a photographer. Once I take some, trying to get them loaded so that everybody can see them might be a challenge in itself.
I'm not sure on the front axle since I can't find my gear catalogs right now (wife cleaned my office - everything's lost). As for top end performance, I've gone from 3.55 to 4.10 to 4.56 to the 4.88's. I never have had my truck over 110 and there was plenty more rpms left in it. I just like the way the 4.88's get it into the powerband faster. I actually never saw a decrease in MPG from the 3.55 to the 4.56. Maybe now with the 4.88's about .25 MPG lower than the 3.55-4.56's. With your taller (heavier) tires the 4.88's would be great. If I can find my gear catalogs, I'll check on the front axle application.