The 6SQ7GT is a double diode triode sharing a common cathode.
The triode is seen at the top with the carbonised anode, the double diodes are seen as the anodes between the triode and the pinch. The screening box is connected to the cathode and the diode anodes are the vertical rods placed either side of the cathode within the screen.
This valve was designed for superhet receiver use where the diodes would act as signal detector and AGC detector and the triode would be the first stage audio amplifier.
The construction has the triode at the top with the electrodes held in place by two mica sheets and a screening box below with two rods as the diode anodes. The anode rods are held by the glass of the pinch.
The wire on the right is the triode control grid connection.
The wide glass tube envelope is 29 mm in diameter and, excluding the IO base pins, is 64 mm tall.
References: Datasheet, 1040 & 1043. Type 6SQ7GT was first introduced in 1939.