In reply to:
Do you even have to worry about vibration from subwoofers in a car like that?
I have no idea, since I don't have a subwoofer, but it vibrates enough on it's own, especially on cold days...
In reply to:
How is the electrical system?
Well, it's as old as I am, so there are problems with corroded connectors and worn insulation leading to hard-to-find voltage drops (my headlights randomly stopped working for a week this summer). In perfect condition, however, it would not have trouble handling modern audio equipment, since the Eldo had all sorts of electrical gadgets already. The '73's even had optional airbags and antilock brakes.
One of these days I'm going to rip out the whole elecrical system and re-wire it, but not until I have a garage to do it in...
In reply to:
Is it easy to work in with respect to Din size ?
The original radios are old-style 2-post types, so the hole in the dash is not even remotely DIN sized. AND the dash panel is 1/8" of solid metal, so it takes a LOT of work to cut a hole in it to fit. Fortunately, I'd already gone to the trouble when I installed my first stereo, so it was just a matter of switching the cages.
In terms of space, however, the area behind the dash, like the rest of the car, is IMMENSE, so you can tuck lots of wires and whatnot back there. Heck, my amp fits up there.
An old car is a lot like having a high-maintenance girlfriend. It can be a complete pain in the ass sometimes, but on a 75-degree day with the top down and the music turned up, you realize it's worth every bit of trouble.