New rear end for 97 Z71 help

One of my friend's son tore the rear end out of his I think its the '97 silverado z-71 body style this past weekend playing in some mud. I saw a picture of the gears and stuff broke in a 5 gallon bucket they had. What do they need to buy just new gears, I mean they don't have to buy the whole hog head and everything do they? I've never had to replace anything like that so I don't know either. Does anybody know how much new gears are? Just a round about figure.

 

Nevermind I asked if they found one and she said yeah its like $1,400 or $1,600 .