Tips on changing rear end gears?

[xtreme80]

I finally got my set of 3.73 gears for my truck.

So this weekend I'll be jumping from a 2.73 to a 3.73. Im gonna be doing the install myself with the help of a weekend mechanic, but hes never touched a chevy rear end before.

Anybody have any write ups, articles, tutorials, tips, tricks, anything I need to know to make this go as smoothly as possible?

It's a 12 bolt. The gears came out of another 12 bolt, but Im not sure if I'm gonna need anything else or not?