Now by dumb luck I just looked in my parts book. The 66 used the LS 2100 bracket. Reason your bracket might be factory:  The Fleetline 66  tractors used a 2-1/2 inch cylinder while the Super 66 used a 3 inch cylinder. The formed piece of metal may be the same and the two pieces were added to hold the smaller cylinder. The Super 66 &amp; 660 as well as all the 6 cylinder row crop tractors used the KS 2100 bracket which is for 3 inch cylinders.