I've got a '04 3500, gas 6.0, DRW, 4WD that I've been using a 8.5 Western Pro Plus in the past. It sags a little in the front. Got a heck of a deal on a MVP3 stainless 8.6 that I plan on putting on it. I figure I need to put stiffer coil springs on the front but the way I read this from rock auto they say RWD only? Would you all go this route or put a set of Timbrens on it?