Has anyone installed the kit that keeps the belt from slipping off the Chrysler

no,you don't need to change water pump pulley.they sell a dual sided V-ribbed belt,which has the groves on both sides of the belt. see rockauto.com for retro fit kit, a lot better price than local parts stores for the exact same or better parts! https://www.rockauto.com/en/catalog/chrysler,1999,town+&+country,3.8l+v6,1353877,belt+drive