The 6073 is a special quality cold cathode voltage stabiliser with stable characteristics.
6073 will maintain around 150 Volts across the tube. The regulation would be 6 Volts for changes in current of 5 - 30 mA.
Made in USA. The cylindrical electrode is the cathode and the anode is the central rod. The horizontal bar is the strap between pins 1 and 4 that support the anode.
The RCA logo.
The thin glass tube envelope is 18 mm in diameter and, excluding the B7G base pins, is 57 mm tall.
Reference: Data-sheet. Type 6073 was first introduced in 1951. See also1951 adverts.