Wheel cylinders for early 65 truck

[lunacy]

I am getting some parts ordered for my truck from rockauto. They list early 65 rear wheel cylinders, and list front wheel cylinders, but only with late 65 rear. What's the difference in the wheel cylinders on early versus late 65 trucks? I am going to upgrade to a 69 dual circuit master cylinder anyway, if I just get wheel cylinders for that truck will they fit my 65 backing plates?

[soopernaut]

They probably have the year wrong but I'm not sure. The 61-64 trucks used a tapered rear axle and many of the parts are different than the newer axle.