Thanks, everyone, for your help! I can see I came to the right place for advice.
The car is home now, thanks to a friend with a truck and trailer. The passenger-side axle had snapped near the outer CV joint, and was being held together by the rubber boot. One new axle later, I was cruising up and down the street! Very happy, so far.
There's more still to do, besides a thorough cleaning, inside, outside and underhood. The glow plug light does not come on. The engine will start, and fairly quickly, and it runs rough for a couple of minutes until it's warmed up. I installed a proper fuse in the relay, rather than the piece of wire a previous owner had installed, and I have six new glow plugs ready to go in. I've read the many posts about glow plug replacement, and I don't expect to have a problem there.
The OM603 has a #22 cylinder head, so I know there's been work done there (the car came with no paperwork).
I'll post some photos when I get a chance. It's Astral Silver Metallic, with a blue MB-Tex interior.