The engine, transmission and brake system were identical in specification to the DV64 and the various improvements and updates were introduced in line with that model. For the DV66 range a slightly different cab was garage door opener springs as the suspension arrangement employed on this model gave an increased chassis frame height, which in turn made the cab sit higher. To achieve the correct wheel-to-wing clearance a cab with deeper side panels was used and the wings positioned some 2/2 in below the door step, as opposed to the standard cab, with the wing placed tight to the door step. The DV66 could also be supplied as a version suitable for drawbar trailer operation, in which guise they were usually fitted with an extra-large, 77-tube, five-row radiator in place of the standard, 39-tube, three-row unit.
These vehicles could be easily identified as having a nose, the grille standing some 2Ain proud of the cab front. 1954 saw the introduction of the final new model to emerge from the Sentinel works which was designated the DV66M and garage door opener springs as the medium six-wheeler. While retaining the deep chassis frame and six-cylinder engine of the heavy type, the rear bogie was identical to that of the light six-wheeler with four-spring suspension and single-axle drive. Two ratios were available 6V4:1 and 5/ă:1 which gave road speeds of 34mph and 40mph respectively.
A slightly shorter wheelbase of 16ft 9Řď was offered for all applications. With the introduction of this model the engine speed was increased to 1900rpm, raising the output to 123bhp. From late 1954 the entire range of both the four-cylinder and six-cylinder engines had the maximum governed speed increased to 1900rpm. The other mechanical details of the DV66M were identical to the DV66 with the exception that to reduce the linkage arrangement to the change speed lever and simplify the adaptation for right and left-hand drive, the David Brown 557 gearbox was mounted perpendicularly, giving a central line for the gearchange shaft from the vertical garage door opener springs turret. The original cab panels were so rotten none could be reused, so new ones had to be manufactured.