with seating for 88 passengers, with either Hercules or Fiat engines. An order was placed with Drewry in the United Kingdom in March 1950 for the railcars with the Fiat engines. Drewry had supplied some smaller diesel shunting locomotives (DSA class and DSB class locomotives) to NZR previously. Due to the progress of the Rimutaka Tunnel (which opened in November 1955), and the impending closure of the Rimutaka Incline, it was decided by NZR to remove the requirement for centre-rail braking and the trussed-chassis required to hold the braking equipment. Introduction The railcars were constructed under subcontract by the Birmingham Railway Carriage and Wagon Company from Drewry. There were significant delays in delivering the railcars, with one (RM 120) damaged in transit, and used as a spare parts source for the other railcars. The first railcar was delivered in November 1954 and the last in May 1958. The arrival of the first railcars was greeted with enthusiasm by local newspapers, and were described as a "new-dawn for long-distance rail travel" in New Zealand. A number of "ministerial special" promotional services were run in March 1955, and the first service operated by an 88-seater railcar was the Wellington-Gisborne daily service on 6 April 1955. Following their introduction, the railcars suffered overheating from ballast dust and engine failure, which led to railcars running 20 to 30 minutes late every two to three days. This was despite two Fiat fitters being in New Zealand as the railcars went into service. The railcars also suffered frequent internal fires, which led to external fires in the farmland and foliage along the tracks. Both types of fire were due to excessive hot carbon particles in the exhaust emissions. These problems were most notable in the South Island on steep West Coast railway lines and the steep Scargill and Dashwood sections of the Main North Line. The crankcases were not strong enough to absorb the power of the diesel engines that drove the railcars. These issues were considered so serious that NZR called a meeting with Drewry and Fiat in March 1957. Ten of the railcars had wrecked crankcases and blown motors. Following the meeting, a number of replacement motors and crankcases were ordered in late 1957. Additional Fiat staff and fitters came to New Zealand from Italy and essentially rebuilt the engines and power systems of all the railcars. The rebuilding was completed in March 1959,