The actual setting up the pre-loads and back lash is not too bad. What takes a lot of time is overhauling all the stuff you get into that is all worn out, Brakes, axle seals drive shaft front bearing and seal etc, etc, etc. Getting everything properly cleaned up is also a job in itself.
I would also strongly suggest that if you are using used axles, get them magnifulxed if you have not already done so. Getting everything all beck together and then a little while later, braking an axle will try your patience as everything has to come out and all apart again.
There is nothing magic about working on a rear axle if you do not get into a hurry and understand and follow the directions.
Again, just my opinion,
Chris