The doors and basic structure of the P25 sedan was retained, and with input from Australian and American Chrysler designers, the 1955 US Plymouth front sheetmetal was adapted to the P25 body and the rear quarter panels redesigned.

They also added a wraparound rear windscreen, which caused development problems with Pilkington Glass, the Australian suppliers, who struggled to get the correct curved shape.

[5] This series featured a new grille and unusual rear styling with additional "saddle fins" grafted on to the existing tailfins.

[2] The choice of six-cylinder and V8 engines continued, with the V8 identified by a V-shaped emblem in the grille and a small V8 badge on the rear quarter.

[5] The new series was easily distinguished from its predecessors by its vertically stacked quad headlamps and triple tail lights similar to those of the 1959 US Desoto models.

The first vehicle was completed in June 1958, after Central District agreed to replace its entire fleet with fibreglass bodied Royals constructed by ComEng.

[10] The use of fibreglass bodywork provided a vehicle that was believed to be tougher, quicker to build, and easier to repair and resulted in a weight saving of around 560 pounds (254 kilograms).