Might as well replace in pairs. If your shocks are relatively worn, the repair is not that bad. If your shocks are relatively new, it is a struggle to compress them and keep them compressed while getting the old mount off and the new one on. A lot easier if you have a helper. As always, extreme caution is advised whenever you are working around the springs. The repair is a cinch if you have spring compressor, a little nerve racking if you don't.

glenmore
1991 300CE
2000 C280