The classic 807 beam tetrode valve is unusual in still being designated as current production in the 1960s and having a five pin base. The 807 was normally run hard and different makes of 807 held up better than others.
The parameters given are for single ended use. When used in a class AB1 as a push pull pair with 600 volts on the anode an output power of 65 Watts was normal.
The anode side view.
The UX5 base. The base shell is plastic not ceramic suggesting commercial ground based applications. For airborne or tropical use the base would be ceramic.
The lower screen and the base of the electrodes.
The classic envelope is 51 mm in diameter, and excluding the UX5 base pins is 124 mm tall.
References: Datasheet & 1040. Type 807 was first introduced in 1938.