The Type 134 is a current probe amplifier for use with current probe P6019, P6020, P6021 and P6022. Serial numbers below 6620 only support the older P6019 and P6020. The current/div is calibrated when the oscilloscope input is set to 50 mV/div. It can also be used as a 50 R input voltage amplifier, with gain of 25 or 125. It comes with a separate power supply.
The internal basic structure is as follows: feedback transimpedance amplifier, emitter follower and voltage amplifier. All stages contain assorted peaking and frequency compensation circuits.
The datasheet can be found on tekwiki.
The emitter follower (Q107) for the power supply, using the casing as heatsink: a RCA 40250, selected at the factory.
The power supply is not much more than a transformer and bridge rectifier. The amplifier unit contains filter caps and simple zener diode regulation with emitter follower Q107 (14 V).