The KT35 is another kinkless tetrode audio output valve from M-OV designed for series heater chains in universal AC/DC sets. In 1951 it was regarded as obsolescent.
For the rated output power the valve should be operated with an anode load impedance of 4,000 Ohms.
The classic envelope is 42 mm in diameter and, excluding the IO base pins, is 104 mm tall.
References: 4018, 1040 & 1043. Type KT35 was first introduced in 1940.