Your memory is fine and you are not hallucinating. Chevrolet never produced a ’58 El Camino. But Joe Cherry did it. 
The car you see here is a unique creation designed and built by Joe Cherry and is called “El Nomado”. While this car looks like it could have rolled off the GM production line in 1958, this is actually Joe’s idea of what such a car would look like if they did.
Joe used a 1958 Chevy Nomad 4-door and a 1958 Chevy Biscayne 2-door to create the El Nomado’s proportions. The Biscayne was used as a vehicle to sponsor longer doors not found on the Nomad 4-door wagon.–
>As you would expect from a car of this caliber, it has been given a number of modern upgrades to improve performance and handling. All brakes have been upgraded to include a master cylinder powering dual reservoirs and now feature circular disc brakes that have been cross-drilled to improve their stopping ability.
The suspension is now fully adjustable thanks to airbags fitted at each corner. The wheels are Boyd Coddington 18 inch Crown Jewel Wheels that work perfectly on the perfect paint.
The car’s interior was designed by Brian Dering and Joe Cherry and matches the line design of the exterior. Inside you can see that all the interior metal parts have been painted to match the exterior and the color is enhanced by the cream leather trim. The Leather trim also continues throughout the folding bed. 
The engine is a 348cc connected to a 2-speed Powerglide Transmission, both available in 1958. The engine is connected to a Tire Warmer Exhaust System with a Flow master muffler. 
What Joe Cherry and his team of master craftsmen have created is nothing less than a breathtaking example of what the 1958 El Camino COULD have looked like if GM had decided to produce the car with Designed in 1958. The results are truly amazing.
