[Buzz]

I thought about NAF - they certainly were around in the early days and they did originally have a narrow-hip style rear fender before switching to the SC look. There are some similarities in the frame and body and NAF did use live axle rear ends.
What put me off from NAF was the interior of the trunk and the placement of the fuel filler; but then some very early bodies did have the filler off center in the body ahead of the trunk opening similar to this car, so you could very well be right. I'll take another look later on.