I installed the Tuf-Tow shoulder harnesses; inertial reels up front and conventional in the back. The way I'd made my aft mounts required standoff bushings, which I'd previously made and painted. The inertial reels require a 0.125 inch strap link to bring the bulk of the unit away from the frame. In addition, the plans call out1/4 inch bolts; but there are differnet size holes in the reels and the conventional bracket. I made a set of bushings to adapt the holes to fit a 1/4 inch bolt. The conventional attach brackets required turning some 4130 tubing stock down on a lathe to get them to fit.
Making bushings.
Inertial reel requires bushings and a 0.125 inch thick strap link.