Pobably 3/4 ton parts, which easily swap with 1/2 ton. The spring hangers are the same, so swapping the complete suspensions isn't too difficult. The 3200 was built doing exactly that, only reversed. It uses the 3/4 ton chassis with 1/2 ton axles and springs, unless the HD rear spring option (RPO 254) was installed. Then it got the base 3/4 ton springs in the rear. IIRC, 1 tons use different hangers for the rear springs due to the different shackle design.
