Allsports make good drop axle and spindle lifts for Workhorses. Their link is at the top of the pages here or on the links page if you want to see pics of what they carry.
That lift seems to have better travel and softer than what I have which just puts the springs on top of the axle. I think its important so that you dont feel every little bump. Idependant A arm is the best but pricey. The rear, be careful if you put HD springs becuase it will ride like crap without a load. JMO