lift keys blocks 3 inch

I have a 2002 GMC Sierra Extended cab 4x4. Currently i have 305/16/70 Mickey Thompson Baja Claws. As of now they dont rub at all and the truck looks alright. I want a 3 inch lift all around. Ive torqued the front up to the max and im afraid the parts will start wearing down. Ive been looking at...