The top shaft in the first picture above is a used 55H for comparision. We made two versions of the D drive shaft. The first is excatly like the original and the second was with five inches of splines at the crank end so it could be cut down to be used in the Mark 40H or the 44XS.  We no longer carry the long spline shaft since they have sold out. The shafts are made just like the originals including heat treating and hardening in the bearing area.