Trouvé sur le net source précise TD qui peut aider.
http://www.mgcars.org.uk/mgtd/mgtd_brief_history.htm
TD
The first model set the stage for what the TD was. Because of the short amount of time from the inception of the TD to the delivery of the first cars, not everything was quite as the MG Car Company would have liked it. In fact they were still making TCs on the production line when the first TDs were being produced. In addition, other cars such as the MG Y-type saloon and the Riley RMA and RMB were also being made on the same assembly line at the time. This says something for the flexibility of the Abingdon workforce and of the factory.
Apart from revised mountings, the engine for the new MG TD was the same 1250cc XPAG unit fitted to the previous model, the MG TC.
There were many subtle changes to the TD, but most were unnoticeable to the untrained eye. One exception was the change from solid steel wheels to ventilated steel wheels. This change was essential because there were complaints that the brakes on the early cars were fading due to inadequate cooling. Another change was to stiffen the chassis by adding an internal steel hoop under the dashboard. This helped to prevent `scuttle shake', although the later chassis still seems to flex quite a bit when pressed into corners.
TD II
In July 1951 the 1250cc XPAG engine received a new block, a new sump, a new bell-housing and a new flywheel in order to accommodate a larger clutch. The engine number prefix was changed to TD2, and MG TDs fitted with this engine have subsequently become known as TD2 models, although contemporary marketing materials did not use this designation. The changeover occurred at engine number XPAG/TD2/9408. (The TD2 should not be confused with the MG TD Mark II, see below).
Several changes were introduced between August and November 1952 as sales of the TD started to fall in favour of cars like the TR2 and the Austin Healey 100. These included circular rear lamps incorporating flashing turn signals, and a three-bow frame replacing the 2-bow frame for the hood. Also, the wiper motor was moved to the centre of the windscreen.
TD/C or TD Mark II
By the middle of 1950 the MG factory were also producing some special MGTD's known as the TD Mark II or the TD Competition Model. These cars were essentially regular MG TDs that had been given some extra factory accessories and tuning equipment. Initially there was no standard specification for these cars, and during the production of the MG TD the specification of the TD Mark II would change.
The only standard feature appears to be the provision of additional Andrex friction shock absorbers front and rear. Some of the modifications on offer included a modified cylinder head raising the horsepower of the engine from 54 bhp to 57, wider wheels, larger tires, higher rear axle ratios, twin fuel pumps, and larger carburetters. You could even have a supercharger. Most of the features of the Mark II were a part of the staged tuning that was described in various publications and offered as a factory tuning manual.
