you could do hangers for the front of the spring for real cheap that will drop 1 or 2 inches, or for an even cheaper route...shackles for the back of the spring, but you will have to cut your bed crossmember(or whatever its called).
for 6 inches of drop though, you will need a c notch or you will be bottoming out all the time...if that werent the case my truck would be 2 inches lower also
