I pulled all the aftermarket audio out of my car and have been looking at returning it to stock-ish, and I thought I'd use this thread to post some more information about the stock radios.
First up, this was the base radio for the VR-4 and the one that came in my car. MB541074

Next up, this is the upgrade radio (the mid-level) for the VR4. MB649791

The next upgrade for the VR4 was the 2-single DIN cd-players. Pics stolen from earlier in the thread as I don't have these.
In 91, we had this one. It requires a separate amp mounted in the trunk.
In 92, the amp was moved into the radio so we got a different tape and cd deck:
Now a few decks I've been playing with.
MB942702 - This particular one came out of a 93 Diamante and I think it's one of the coolest Mitsu OEM radios

and at night. Doesn't quite match the deep green of our backlight. It's more of a yellow-ish green.
There are a few variations on this radio. MB942704 was used in the Mitsubishi 3000GT and is exactly the same with the exception of the backlight colors:
MB629129 is also similar. It's from the 91-92 3000GT and while it doesn't have CD changer control like the MB942702/MB942704, the radio plugs match what's in the Galant.
However, all you need to do to get the MB942702/MB942704 radios working is to put together an adapter harness:
You also will need to redrill the radio brackets, as the radio mounting holes are in a different location. They are also anti-theft decks, but you can get the radio codes from Mitsubishi online for free.
Finally, all the part numbers are what I was able to find. There are other similar-looking radios out there but with different part numbers. Some of that is because the backlight is a different color, so double check it to make sure you get what you want.