I'd be very leery of putting 4.56's in a D35C, seriously. I killed my D35C with 3.07's, 30" tires and an EZLocker. Now, my axle housing is about as straight as a San Francisco transvestite...
If you want to go ahead with 4.56's in your current setup, you need to know what your current ratios are. If you currently have 3.55's or lower, you will need new carriers front and rear. 3.73's and higher use a different ring gear carrier. This holds true for both front and rear axles.
You'll also need bearings, a shim kit, and appropriate gauges to set your gear backlash. In other words, if you've never set up a differential before, you probably want to take it to a driveline shop and let "the pros" handle it.
If you screw up your setup, you'll eat your gears alive in no time - definitely a "bad thing."