I notice my 4.3L V6 Silverado sags down big time when a lot of weight is added inside the bed. Does my truck not have as strong suspension in the rear as the V8's? For example, if I stand in the back of my truck and jump up and down, the truck lowers drastically and it's like I have a low rider. Granted I weigh 288 lbs. but what if I need to haul a large bookshelf (ect.) which would be heavier, what can I do? I want it so my truck wont droop down when hauling heavy stuff, or towing a heavy trailer. How can I solve this problem?