Question: how to change gvwr on truck?
Answer: Identify your truck's weakest link by researching its weight-bearing components. For example, say a given truck has a pair of Dana 44 axles rated at 3,500 lbs. ... 
Replace or reinforce the weakest link with something of a higher weight rating. ... 
Replace the next weakest link. ... 
Install a set of heavier-duty axles.