The VU134 is a half wave EHT rectifier. It would have been designed for provision of EHT in such applications as Cathode Ray Tube indicating instruments. Radar and Oscilloscopes primarily.

The white tube is the oxide coated cathode. The separation of the cathode from the anode suggests its high voltage design.

The classic envelope is 43 mm in diameter, and excluding the B4 base pins, is 109 mm tall.

References: Datasheet, ¹⁰⁴⁰ & ¹⁰⁴³. Type VU134 was first introduced^¶ in 1937.

 
Pin Connections

B4	1	2	3	4	tc
	-	-	h,k	h	a

 
Absolute Maximum Operating Conditions^¶

Rectifier	Vh	Ah	Va	mAa
	4.0	0.65	6000	3.0

Thanks to Frank Philipse for supplying the above PDF datasheet