The U.S. Heartfield R&D Design Team The U.S. Heartfield R&D Design Team.pdf 100 KB Download Related articles The Who, What and Why of Heartfield. How can I find out when my American-made instrument was manufactured? Are There Any Online Resources For Information On Heartfield Instruments? How can I find out when my Japanese-made instrument was manufactured? Heartfield Parts Lists And Wiring Diagrams