On the W124, the original mounts were solid rubber, replacement FRONT mounts are gel, rears are still solid. I don't remember which of yours appears to be leaking.

I know it's not your brakes or shocks!

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!