Just my .02 but widening it 4" would be a pita. If your looking for more room inbetween the rear wheel wheels you can put a set of 2" spacers onto rear axles to move the tires out a total of 4" get a set of rims with an extra 1" of back spacing and your reduce the width of your wheel wells by up to 6" (3" per side) with out widening the tub. If you add 4" down the middle you will still have to either add the spacers to the axles. Then move all the feame mounts out 2", resign the steering column linkage since it will be moved 2" towards the frame. The. There's the hood, and grill that have to be widened,new radiator mounts to be fabbed since the grill will now be wider, new glass for your windsheild . By moving telhr wheel wells you will he the 4" you need with out havin to get crazy fabbing stuff