G'day Nick-S

This is a new one on me - Fowlerrex Supa-Swift.
It is a modern iteration of the Supa-Swift Hi-arch.

The blade holder and blades are not Supa-Swift.
That is a universal blade holder with UTA blades.
Try https://www.gaspares.com.au/

However, my first call would be to:

Rosanna Mowers
Contact details
(03) 9457 2330

They should be able to tell you whether the holder and blades
were original fitments.

Hope this helps.
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Jack