11. Fully welded, and ready for heat treating: Most trailing arms are not heat treated, and seem to do just fine without this extra step. If you’re building with a heat-treatable steel alloy, and you want the ultimate in strength, heat-treating is worth looking into. If you are fabricating your own trailing arms, do yourself a favor and build them to mount two shocks, even if you have to start with coilovers only. Trust us: You will want the performance of bypass shocks later on.