Steve...the "Dragonsnake" concept ended up as an optional factory-configuration that could be ordered from SA for a drag Cobra.... several were sold.
However, it originated with a factory-campaigned car that was active in local SoCal drags as a publicity car for SA.
From earlier discussions, I have this list of known Dragonsnake configs:
CSX 2019------
Factory PR Dragonsnake
CSX 2093------Famous Costilow/Larson car. This was an independent car, non factory built, perhaps the most famous of all the DS cars.
CSX 2248------Factory built for Customer (the El-Cid car)
CSX 2353------Independent (Siebens-Sidel car. )
CSX 2357------
Factory car (second one built)
CSX 2427------Factory Prepared/independently campaigned.
CSX 3198------Factory Prepared car for Harr Ford. Only 427 built.