If your SL doesn't seem to absorb those little bumps like it used to or if you hear "clunks" in the suspension when hitting bumps then you probably should try to change as much rubber suspension bushings as you can.
Brittle rubber does not make for good road absorption. I have no idea what type of suspension you have in your '73 SL but I would begin by changing the front sway bar bushings. These bushings absord alot of the little bumps that the shocks and struts can't compensate for.
'91 300E, 207k miles