The 6X5GT is a standard HT rectifier for low power AC mains driven equipment. It was of a type made by several manufacturers, in this case RCA.
The output of a centre tapped transformer would be applied to the anodes, the rating given is 325-0-325, the common cathode would be the output for the rectified voltage. A effective series resistance of 350 Ohms was required to limit surges and the reservoir capacitor had to be restricted to 16 µF.
The anodes end on. Most implementations of this rectifier Type use stacked anodes on a common cathode and each side of each anode radiates heat. Here a pair of single sided anodes are mounted either side of the whole cathode length.
The anodes are offset from the centre line. One support rod per anode and the spacing is maintained by slots in the mica supports.
The wide glass tube envelope of the top valve is 29 mm in diameter and excluding the IO base pins the valve is 61 mm tall.
References: Datasheet, 1040 & 1043. Type 6X5GT was first introduced in 1936.