The KT32 was designed as an audio output device in universal sets with a 300 mA heater chain. The 3.5 Watt output was to be had with an anode load of 1,300 Ohms.
The classic envelope is 42 mm in diameter and, excluding the IO base pins, is 105 mm tall.
References: Datasheet, 1040 & 1043. Type KT32 was first introduced in 1937.