Need advice on shockers
 

1994 C180 Euro requires new shocks front and back. Do I have to change the springs too? Front shocks feel hard over most bumps, not leaking. Rears have oily leak marks, also hard over bumps, but have the H1 number printed on the cylinder. Other same model C180 I saw have the H6 part number on the cylinders. Can some one please tell me which has the "right" ones and also whether H1 means harder shocks and H6 mean softer shocks or its only a new replacement part number?