I have to agree with Gunslinger, look into better speakers. Forget about the GM speakers, especially if they're the older type, you'll never get the sound out of them. Everything is relative, you could have a top of the line head unit, but if the speakers don't match or are of poor quality, you'll get crappy sounds out of it. The same will apply if you reverse the process, great speakers, but cheap radio will result in the same crappy sound. Boston Acoustic and Infinity speakers are the way I would go.

I have an Alpine radio with the Infinity's, they sound awesome !

I heard that the metal chrome box that fits over the distributor and coil was put there for better radio reception.  Is this true or B.S?

The box isn't for better reception per se...it's there to shield the radio from RF (radio frequency) interference. Metal cars do this since the car body itself acts as a shield. Fiberglass has no natural RF shielding ability, hence the metal shield around the distributor and coil, and metal shields covering the spark plugs wires on a small block Vette and the metal sleeves over the plug wires of a big block.

Try a factory radio in a Vette with the shields removed and you'll hear the difference...particularly on the AM band. Modern radios are better in this regard, but you can still have noise interference and may require filters or shields as well.

I agree with Custom Autosound. I put one in my 71 with some good 3 way 6x9's. The radio is suppose to be 100w. It sounded like crap & I did everything to get rid of engine noise. I put in a 200w amp. Still sounds like crap!! I like others turn it off and listen to the engine purr. That's some of the best music I know. Terry

There used to be a fellow from Colorado on the site who had bezels available for after market radios.  Can't remember his name or handle at the moment but if it comes to me I'll post it. (Ain't "muddle age" wonderful!  "Mental pause" is such a calming experience!    )

I replaced my factory radio last year in a 1978 vette. Ordered an am/fm/cd from either mid am or ecklers it came with a new center console dash and it works great all you have to do is change out the instruments and it still looks factory and you can store or sell the original console plate.