C3 conversion for CSX style chassis

[my427cobra]

This concept of using a C3 diff has really got me thinking and also has left me with some questions.

Can any of the experts answer this question for me:

Why did the original 427 Cobra rear suspension use a Spicer splined half shaft?

I would have thought with fixed length upper and lower a-arms the half shaft would be a fixed length also.

Or was it because the original rear suspension used rubber bushings which allowed for a lot of suspension "movement" and therefore required some "slip" action in the half shaft?

Can anyone give a simple explanation?

And if one used fixed a-arm joints (hiems or poly), would a fixed length half shaft like a Corvette C3 half shaft work?

So many questions!

Cheers
Greg