I am running 39.5 boggers, locked FF14B, locked D60 with 35 spline in and out, doubler, SM 465, and a 500 hp 454. this compition I am prepairing for has tug of war, rock garden and the mud bog. I have ran for practics all of these more then once and may have fractured the joints before I blew them in the mud. Also they blew when I had the wheel cranked and in revers.