An all-composite driveshaft incorporating integral flexible diaphragms is described and proposed for phase II prime conractor testing. The approach obsoletes the split lines required to attach metallic flex elements and either metallic or composite spacing tubes in current solutions. Sub-critical driveshaft weights half that of incumbent technology are achievable for typical rotary wing shaft lengths. Spacing tubes are described, which comprise an integral part of the initial tooling but which remain part of the finished shaft and control natural frequencies and torsional stability. A concurrently engineered manufacturing process and design for performance is described which competes with incumbent solutions at significantly lower weight and with the probability of improved damage tolerance and fatigue life. This phase II proposal seeks to produce additional fatigue test articles to supplement the pair of shafts provided during phase I for static evelauation. The phase II effort will also support the prime contractor test program designed to raise Technology Readiness Level to 6-7.