This type of repair is generally considered moderate to difficult for new mechanics to do. It really is straight forward though. Setting the pinion depth and backlash are the 2 things that generally are done wrong by a first timer. There are a few tools that are required also, like a dial indicator, larger than "normal" sockets, and the corporate rear-ends also require a special side bearing tool (used to adjust backlash and side-preload). Although this special tool can be fabricated fairly easily in a pinch.
Just be sure to replaced the bearing races also.
I doubt that the carrier bearings went out because of the u-joints, but the reason behind the u-joint failure may cause excessive wear on the carrier.