http://www.carnut.com/specs/rear.html

Here is a link to a site with a lot of info. This couple of pages is just one of the many things he has for one to peruse; and, they have probably more info than you wanted to know.

If I were you, with a Dana 44 that fits the truck already there, I'd be inclined to rebuild it with the gears I wanted, rather than going to the trouble of cutting, re-fitting, and machining the 9 incher. It all depends on what you want to get from the truck, though; if you're just going to cruise it, with a mild engine, the Dana will serve very well. As to cost, I don't know for certain, but I feel rather sure that re-gearing the Dana will be less expensive than shortening the 9 inch. If you just must re-fit the 9 inch, consider taking it to Currie in Anaheim; they are the premier 9 inch gurus. Heck, give them a call and ask their opinion on your needs.