classes came to existance after 1993. This car only is a 200 - which literally translates to 2.00 litre carburettor engine.
The 230E that you see commonly in a W124 is 2.30 litre "Enspritzen" meaning fuel injection engine. Similary the D stood for diesel and T stood for touring wagon.
similarly the 280E and 300E were enspritzen too, The only carburettor engine W124 was the 200.
The S in earler cars stood for "sonderklasse" which translates to special class - usually on the largest bodied sedans or on the most expensive coupes.
So the early 280SE stands for 2.8 litre enspritzen sonderklasse. If it were SEL - add "Lang" (long) for sedan or "leicht" (lightweight) for sports coupes.