Disclaimer: no offense is intended to those interested in maintaining their original radio, this is simply a different opinion for those who like good sound.
Ok, its one thing to have an antique vehicle, but antique sound just doesnt make sense to me.
For those of you looking for quality in your sound here's the way to go.
Install a modern am/fm cd,mp3 player where the am radio was.
Put two 4 inch speakers in the regular spot you would normally have that joke of a mono-speaker in the dash.
Then put two 3.5 inch speakers in the top front corners of the cab, you will have to adjust the balance down just a little on the cd player for the 3.5 inch speakers to properly balance your sound.
Then get a Kenwood subwoofer, they make a type which happens to fit perfectly under the bench seat and you have a kick-[censored] system for $500 canadian.
This is not a system that will cause earthquakes or broken windows it is just a real good all round sound with ALL the sounds available. You will notice I also have not installed an amplifier, so far I am getting enough out of the sound without one, but for improved sound I would suggest an amp under the bench seat which also will fit nicely and unseen.