I just did this on my 1991 300CE. You might have another person handy to bleed the system. Before loosening anything, clean carefully around the flange where your new hose attaches to the thin metal line. Lots of grit there plus you'll then see the 12pt cutout for the upper fitting of your new hose. Wipe up any brake fluid immediately.

glenmore
1991 300CE
2000 C280
1990 LS400