You will want to use the Roadmaster Comfort Ride Leaf Spring Suspension Kit w/ Shock Absorbers # RM-2460-2560. This system is for axles and suspension rated up to 5,000lbs. Since you are not increasing your weight capacity these will give you the best ride quallity.
The Roadmaster Comfort Ride Leaf Spring Suspension Kit w/ Shock Absorbers # RM-2460-2570 having the heavier 7,000lb springs will create a rougher ride with the stiffer springs.
I recommend having new U-Bolts w/ Nuts for... view full answer...