I have an 84 coupe which is basically all original except the PO had put a modern head unit in the car, though not modern enough to easily connect to an IPOD.
When I first bought the car, I put in new door speakers powered by a small amp under the passenger's seat and really desired to put back in the old Blaupunkt Monterey HU. My intent was to have it there but unconnected, and connect my Ipod directly into the amp.
The problem is that the Ipod puts out much less amperage than the amp prefers.
So I solved this problem by purchasing a JL CL-RLC, link below
CL-RLC - Car Audio - OEM Interface - System Expansion - JL Audio
This is an active level control pre-amp to boost the amperage up so you can directly attach an Ipod to the amp. It has a separate volume control knob, which I have not mounted yet.
I opted to mount the unit in the shifter console, completely concealed. I still need to make a non-permanent Ipod dock, and figure out where I can mount the volume control.
lastly I'll need to go and re-adjust the gain on my amp. I found the sound to be awesome so far though. it's way clearer than it was when i was trying to connect my Ipod through my head unit.
Best part is this thing was only $60! For those looking to retain the stock look, but have really great sound quality this is the way to go.