Borgeson - Steering Shaft Support - P/N: 670600 - Steering Shaft Support Bearing. Billet Steel. 6 In. Long Cut And Weld Style. Supports All 3/4 In. Splined And Double-D Steering Shaft.If more than two joints are used in a steering system, a support bearing must be used to prevent "looping" and binding. Use of a vibration reducer and two u joints will also call for a support bearing to be used. A system with a double u joint and a single u joint has three flex points and will require a support bearing. Support bearings will work with all 3 4" splined or Double D steering shafts. All billet supports accommodate a 3 4" shaft. Our