Manufactured by Radio (1936) Ltd in 1959.
The Ultimate Transistor 8 'Explorer' - possibly the first transistor radio from Radio Ltd.
Assuming its functional, wiring in a 9V battery or a 6 x AA (or C or D) battery holder to give 9V should get one of these up and running.
Valves (8 Transistor ,1 Diode): 2N544, 2N412, 2N412, 2N412, OA85, OC71, 2N406, OC72, OC72
Intermediate Frequency: 460kc/s
Chassis code RDM - this might not be visible on the chassis but is documented in the schematic.
General Construction Notes for Radio (1936) Ltd: Early Radio Ltd. schematics did not show the models, just the year, valves and bands, so some sleuthing is required to find the right one.
Early 30's Ultimate models with three digit model numbers indicated both the number of valves in the set, and the price it retailed for - for example, the model 856 was an 8-valve radio which retailed for $56 pounds. The equivalent Courier models were reversed, so an Ultimate 856 was a Courier 568 (theoretically, at least). This was the Auckland price though, and often the sets would retail for 1 or 2 pounds more in other centres, presumably to cover the freight cost of moving them around the country from the Auckland factory.
Note the use of old resistance terminology on older schematics: ω means ohms and Ω means megohms.
Some 1936-onward 3-letter chassis codes vary the last letter between brands, for example:
BBU - Ultimate model BB
BBR - Rolls (and Golden Knight) model BB
BBC - Courier model BB
All use the same chassis.
Golden Knight, Courier and Rolls appear to use the same copper-painted chassis while Ultimate chassis' are painted silver