I'll save you the trouble:
DG, the early type of auto box on the MK I and MK II Rover P5s [it was a BW (Borg Warner) - Detroit Gears (DG)], . MKIIIs and P5Bs had the later BW35 gearbox, though with different selector controls. BW35 was being looked at by Rover for the P6 2000 and was found to work with the P5, which also enabled the auto gearbox to fit/work with the same specification 3-litre engine as the manual transmission cars, simplifying production.
IIRC - If I Recall Correctly.
That's all AFAIK - As Far As I Know