Abstract: A downhole vibration tool that permits tool retrieval therethrough has an outer housing with an inner bore and a longitudinal axis, a rotating impeller that rotates within the inner bore of the outer housing, the rotating impeller defining an outer flow passage and an inner flow passage nested within the outer flow passage. The rotating impeller carries impeller vanes that are angled relative to a rotational axis and that extend into the outer flow passage such that fluid passing through the outer flow passage impinges on the impeller vanes to cause the rotating impeller to rotate. A flow restrictor having a variable flow area is positioned in the outer flow passage adjacent to the impeller vanes, and the rotation of the impeller vanes causes the flow area of the flow restrictor to periodically increase and decrease.