It has been about three weeks since I upgraded my rear breaks. I used a gmc dually 1 ton rear wheel cylinder. The parts guy was interested in what I was doing and brought out a ½ dozen wheel cylinders for me to inspect. The new cylinder is considerable larger in length and diameter.

The gmc wheel cylinder fit like there were made to be there. The difference in performance and feel are impressive.

Whitmore has a great write up regarding the upgrade