I have one that started out life as one of those I think. Was re-cored with the later model staggered 4-row core and had a neck added.
Reason I think it was one of the early tanks was that with the neck mounted you could not install a radiator cap! The upper mounting clamp was too close because the tank was so shallow.
I have seen tanks that had what looked like a circle that was capped off, where a filler neck would otherwise go. Maybe they used that to retrofit the neck and it didn't work. So I had it extended up so it cleared the mount just to do it.
I don't really need the radiator, so will find someone local that can use it.
Paul