A slider window assembly for a vehicle includes a movable window panel that is movable at a fixed window panel between closed and opened positions. A lower end region of the movable window panel moves along a channel portion of a lower rail and an end stop is disposed at an end of the channel portion. The end stop includes a rigid base portion attached at the lower rail and a resilient elastomeric stop portion attached at the base portion and configured to engage an end portion of the movable window panel when the movable window panel is moved to its fully opened or fully closed position. The base portion and the stop portion are separately formed in separate forming processes. When the base portion of the end stop is attached at the lower rail, the stop portion is fixedly attached at the base portion and is not removable therefrom.