W124 arguably the best chassis for passenger cars in modern times....build quality on it blows any new car away. He's right too...pretty easy cars to DIY and other than the normal maladys the cars suffers from, it is as relaible as they come...
Your wife will forget the maint. bills after she drives one I'd like to think.
A ton of info here to search on the car; after a few hours you will be a most informed potential owner. Probably one of the biggest worries , as said, is the wiring harness; which isn't such a big deal IMO and cheap and easy enough to replace yourself in the garage in a few hours. Go for it...I'd jump at any W124 driven by a little old lady myself !
