Don't let the bare body scare you. In 1972 and 73 Shure eliminated the labels from some elements, and stamped the date code directly on the chassis. What matters most is tone, and this one is bright and Hot. The 99S556 elements came stock in Shure 520's and are super-strong why high output, 1373 on this one.
Manufactured: October 1972
I've personally tested this element in a Shure Green Bullet shell and played it through a Kalamazoo Model Two, and custom Mission Chicago Harp Amp.