From RROCA-info

Number produced: 3,072 plus 35 long wheelbase
Original Specification: (same as Silver Cloud) 6 cylinders, overhead inlet and side exhaust valves, 92.25 mm. x 114.3 mm. (4887 c.c), single plate clutch, 4 speed automatic gearbox, hydraulic front and combined hydraulic and mechanical rear brakes with servo, suspension independent front and semi-elliptic rear, wheelbase 123", weight (complete car) about 4370 lbs., tyres 8.20 x 15.

Chassis Series	Year	Comments
B 2-500 AN	1955/56
B 1-501 AP	1955/56
B 2-250 BA	1956
B 1-251 BC	1956
B 2-500 CK	1956
B 1-501 CM	1956
B 2-350 DB	1956/57
B 1-351 DE	1956/57
B 2-650 EG	1956/57
B 1-651 EK	1957/58
B 2-650 FA	1957/59
B 1-651 FD	1957/59
B 1-125 GD	1959
B 2-126 GC	1959
B 2-50 HA	1959
ALB 1-36	1957/59	Long wheelbase (127")