This is a Mazda version of the ECC83 and is an imported or foreign type. The use of the word foreign in the middle of the 20th century had an undercurrent of inferior to it.
The ECC83 high impedance amplifier triode was designed specifically for audio use and has a high amplification factor of 100, primarily intended for use as a resistance-coupled amplifier or phase inverter.
The reverse of the envelope with the announcement of foreign origin.
The thin glass tube envelope is 21 mm in diameter and, excluding the B9A base pins, is 48 mm tall.
References: Datasheet, 3002 & 1040. Type ECC83 was first introduced in 1954.