i have an 08 f250 and i haul occasionally. i do alot of mulch delivery, and even a truck full of mulch in the bed makes the rear end sag more than i think it should be. i have 130,xxx miles and i think that my leaf springs might need to be replaced? i had a 2000 f350 and i couldnt do anything to get that truck sag at all and i miss that. i am thinking about upgrading the rear end set up to f350. if i am correct the difference is different leaf springs and a taller block. should i replace the leaf springs or just do an add-a-leaf? should i go to the ford dealer and get the specific block that it should have on the f350? do leaf springs wear out like that? or am i just imagining things... i know thats alot of questions but any help would be great.