I got the new stereo head unit installed. And (most of) the remaining Con Ed equipment out. I had to tear apart the dash bezel, both lower dash panels, the passenger kick panel, and peel up the passenger-side floor mat. Gawd, what a hassle! There's still more of Con Ed's leavings, but that's for another day.
Here's the new unit: an Alpine CDE-9872. It's a marked improvement, even just playing through the two factory door speakers.
As I was re-connecting the negative battery cable, I noticed a wiggle in the positive cable/terminal connection (which I hadn't messed with). Turns out that the threads in the battery's side terminal are completely shot. Anybody got a reliable fix for this, or do I need to buy a new battery?