 For the Rover 800, there were two different versions, with single point fuel injection (for the Rover 820e) or multi-point injection (for the 820i).The M series uses the same cylinder block as the O-series unit as found in the Maestro and Montego, which mates with the Powertrain Ltd PG-1 manual gearbox.These were also used in the Morgan Plus Four, the only rear wheel drive application this engine was used in, meaning these can be put in rear wheel drive layouts using the Rover LT77 transmission 

In 1990, the M series was also installed in the Rover 200 series, before being superseded in 1992 by the similar T series which was a development of the same design.