For Trade Have extra Canon FD25 extension Tube. Want Canon FD-50 extension tube

I have an extra FD-25 life size (1:1) adapter for the 50mm f3.5 FD macro lens. I need the FD-50 adapter for the Canon 100mm f4 macro FD lens.

Swap?

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Bump. Swap for or purchase FD50 extension tube.