These are the drive plates we use in our Camburg 3.25 TT rear race hubs. They are CNC machined in-house from 4340 chromoly, broached, then heat-treated, stress relieved and electroless nickel plated for corrosion resistance. They are the 6 on 6.5" bolt pattern with either 36 TT splines or 40 spline for the full float axle shafts. Unlike some, we precision broach our axle splines for a tight fit.