9. After bolting together the cradle assembly, BOS used pole jacks to hold the cradle brackets in place on the framerails, but you could also use C-clamps. BOS then measured from the flat, vertical section of the undercarriage to the lowest corner of the shock mount bracket. The ideal number is 10.5 inches. This can differ slightly so long as both driver and passenger sides are the same. In our case, the measurement came in right at 10.5-inches.