mayo30, Smiley's in Mount Vernon, Wa installed spring pads on the top of the axles and raise the trailer and moved the jack plates to the lower hole to give a 3.5" increase in height to level the trailer. The trailer cam OEM with sub-frame below the I-beam. Shocks were OEM with new lower mounts add when it was raised. One of the new lower mounts broke loose from the axle a few years later and Smiley's repaired it. The cross tubes were added a few years later after fixing cracks in the I-beam webs. Trailer was much better after the repairs and cross tubes. Chris
One of four fish plates place over repaired cracks, with plug weld at place of crack.
Here is Lippert bulletin on installing the cross tubes.