I don't know what the Viper stuff costs, but even IF the change was made from pin to slider, the additional parts wouldn't cost that much money. Reman calipers are $25 each, pads would run about $20, and hoses are $5 apiece, so $80 more to go to the pin type.

Of course when I pull that stuff in a pick-a-part yard, it all comes with and usually costs $50 to $75 a side. And that includes the spindle and rotor. Sometimes, it is even fairly new reman stuff.