I will probably truss my 12 bolt soon. I plan to use a 1 5/8" round tube. I will bend it to reach from each spring perch to above the center section. I will then weld 1/4" plate to fill the gap between the axle tubes/center section and the new brace. I may drill some holes in the plate to lighten it after welding it. You may want to check some back issues of Fourwheeler (last few months) or 4 wheel and off road. I saw a truss for this type of axle that had a removable section to access the rear pan. I think the person above was correct in stating the truss would work better in tension than compression, however it I dont want the low hanging, mud dragging, truss on the bottom. Either way, it is going to help...
<font color=red>Mudzer</font color=red>
1978/91 K5 Blazer