Here is some info on the MorRyde X;Factor brace. In doing the search for this link, I noted that it was shown to be available on E-Bay and Amazon.
https://www.morryde.com/products/x-factor-crossmember/
Years back, I had a terrible twisting of the 2 I beams centered on the axles. My independent welder straightened out the I beams as much as possible, removed the unsavable portions, bridged those portions with thick wall rectangular steel tubing, and made crossbracing like the X factor out of the same thick wall steel tubing.
Part of the Mor Ryde IS installation frame modification is to build a steel tubing "box" between the I beams within which the IS axles are installed. Again, this controls I beam twisting.
BTW, the MorRyde IS
eliminates conventional spring suspension springs, hangars, bushings, wet bolts, U bolts, and equalizers.