Take a look, it's easy to tell -- the largest diameter "rim" at the base of the steel portion of the mount should be nearly an inch above the frame and dry.
If you cannot see (or feel) the trapezoidal portion at the base of the mount, it's shot.
They aren't exepensive and other than the difficulty in accessing the upper bolt on the driver's side, easy to replace.
A floor jack with a boark on top will work fine -- the bottom of the oil pan is flat and you aren't lifting that much weight. If it still bothers you, make a jig to lift on the AC compressor or the crank balancer instead.
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!