Edge

The replacement on my 81 300SD was not very difficult. Took about an hour.
There are two or three? allen head screws on the top of the mounts, and one larger allen headed screw underneath.
The topside screws are not hard to remove, there is one on the inside that has some access problems.
The large screw under the frame can take some effort to remove. You need to go through a hole in the frame to get to it. It sits in the center of the mount itself. Use a good light to locate it. The problem is that it is set into aluminum. It gets stuck easily. I used an electric impact driver to loosen it. I just let the wrench rattle on the bolt for several minutes, then I used a breaker bar to get it out. Be carefull not to round out the bolt head.
I have unbolted a couple of these mounts and seems there is at least one bolt in there that can take a while to loosen. I replaced them with anit-seize compound. Should come out easier next time.
Oh, did I mention you need to raise the motor after the bolts are loose?