It will be hard to steer with stock steering when four wheel drive is engaged, it is also hard on parts. It will be almost impossible to drive on the street in bad weather. Plan on upgrading your axle shafts and u-joints. Make sure that the person welding it is capable of doing it right.
If you are going to do that buy a mini spool instead....that way if you don't like it you can pull it out. Once it is welded, you would have to replace everything and a mini is a lot cheaper! I think Fourwheeler did an article a few months back on welding up the spider gears.
it's an assembly that replaces your spider gears in you carrier so that the axleshafts are always 100% locked, like an ATV axle. They usually come in two peices so you dont have to dissasemble the ring gear from the carrier. If you want to do the same for the rear, get a full spool that is a solid chunk of metal that replaces your whole carrier and decreases the risk of breakage.