Ford has a website that lists E-Series changes by year. I can't find it just now, but I remember that along with the change in rotor size in 2008, they changed the nature of the pad material as well.
I think the conversion companies WILL sell just the brakes or just the axles. At least I had that impression from an OP here who was getting parts from Quigley. A very late model, low mileage, well kept chassis might not need the axles replaced to get new bearings and ball joints, If it has any significant age/miles, only makes sense to change axles as well. Less expensive than parts only later.