The back end of my truck squats a little. I have a 6 in lift but I believe the front is tourqued up a bit giving my truck a squating look. It already has a 2 in block, but I dont know if I should use a 3" 3.5" or 4" block to raise the back to level or just above.

 

An add a leaf or new leaf springs are the way to go. When the blocks get to high your asking for problems.

My two cents.