Design 1335 Goose

This one has me scratching my head. This is actually the original 6-meter Goose, design #243, launched in 1938. In 1957 she was completely rebuilt at the Luders Yard in Stamford, Connecticut but with completely new strip planking. Then in 1971 her after sections, rudder and transom were heavily modified to what you see here. Yet the boat today seems to have the original transom. So at some point she was again modified, back to her original configuration.

So my questions are: why did we assign a new job number instead of simply giving the job a "C1" extension like we would normally do? Who would do this to such a beautiful boat as Goose? And when did it get reversed?

Here is the original sail plan.