Lift, axles hold up

[Kerr]

A friend of mine just installed a 6" Super lift? or maybe it was rancho.. I cant remember. Anyway he is running 40" Swamper radials. I ask him how it will hold up to the extra heights and weight of the tires. He said " Aint got a clue"

So my question to you is,
How will it do? Also if you where to regear one what would you do? 4:56 4:88? and how well will that hold up?